CAIRO—Tens of thousands of supporters and opponents of Egypt's president clashed Wednesday, hurling rocks and Molotov cocktails and brawling in Cairo's streets, in the largest violent battle between Islamists and their foes since the country's revolution early last year. 
 
 The confrontation started in the evening after Islamist protesters marching in support of President Mohammed Morsi, a former leader of the Muslim Brotherhood, moved to break up a demonstration by the president's non-Islamist opponents outside the presidential palace in Cairo, where Mr. Morsi has his offices. 
 
 Supporters of the rival camps, spurred by public defiance by influential figures on each side, waged back-and-forth battles in side streets outside the palace walls as night fell, shutting down major thoroughfares. Around midnight, police formed a barrier between the camps, with thousands of demonstrators on each side, as gunshots rang out and each side accused the other of firing live rounds. 
 
 Those allegations couldn't be confirmed. More than 120 people were wounded, Egyptian medics said late Wednesday. The Muslim Brotherhood said at least one of its supporters had been killed, while opposition officials said two of their supporters had died. A local television channel, ONTV, showed images of two people it said were killed in the clashes, and said violence was spreading elsewhere in Cairo. 
 
 The Obama administration exhorted the sides to respect each other and refrain from bloodshed. Secretary of State Hillary Clinton, speaking in Brussels, called for a two-way dialogue. She also expressed dismay at the constitutional process, saying Egyptians "deserve a constitutional process that is open, transparent and fair and does not unduly favor one group over any other." 
 
 Also in Cairo, crowds besieged the Brotherhood headquarters in the al Moqatam neighborhood, ONTV said. Protesters also burned down a Brotherhood headquarters in the Suez Canal town of Ismailiya, Egyptian media reported. 
 
 The conflict between Islamists and their opponents has been behind some of the Middle East's bloodiest civil wars. Those who battled in the shadow of Cairo's presidential palace mirrored Egypt's secular-Islamist divide—with a crowd of mixed-gender and mainly young Egyptians, many in tight jeans and hipster haircuts, facing off against men in conservative dress shirts or robes and skullcaps. 
 
 Egypt's opposition was galvanized last month when Mr. Morsi issued a decree granting him nearly unrestricted powers and placing him above the judiciary. The decree paved the way for hurried approval of a constitution that was drafted by an Islamist-dominated body that the opposition says was working illegitimately and produced a charter weighted with Islamic law. The government has set a referendum on the draft for Dec. 15. 
 
 Anti-Morsi Egyptians took to the streets. On Tuesday, they marched on the presidential palace to denounce Mr. Morsi, the first time in recent memory that protesters made it to the palace walls. On Wednesday, Muslim Brotherhood leader Essam El-Eryan, speaking on al-Jazeera, called on millions of Egyptians to go to the presidential palace to "defend the state and its legitimacy." 
 
 Mohamed ElBaradei, one of the leaders of the opposition, countered on Wednesday that Mr. Morsi had lost all legitimacy. The president, he said, bears full responsibility for the current violence and is in danger of drawing Egypt into "something worse." 
 
 Speaking in a televised press conference, Mr. ElBaradei was flanked by Egypt's top opposition leaders, including ex-Arab League chief Amr Moussa and Hamdeen Sabahi, both former presidential candidates. It was a rare show of unity by Egypt's historically fractured opposition forces. 
 
 "We will not enter any dialogue until the constitutional decree is rescinded and the constitutional referendum is postponed," said Mr. ElBaradei, adding that they will pursue "any means necessary" to restore democracy and dignity to Egypt. 
 
 A Muslim Brotherhood spokesman, Gehad al-Haddad, accused Mr. ElBaradei and other opposition leaders of inciting violence. He wouldn't rule out that Mr. Morsi could order their arrest on those grounds. 
 
 Egypt's public prosecutor, who was appointed by Mr. Morsi, on Tuesday ordered an investigation into allegations by a private citizen that Messrs. ElBaradei, Sabahi and Moussa, among other opposition leaders, were conspiring with Zionists to overthrow Mr. Morsi's government. The three didn't address the allegations. 
 
 At the palace early Thursday, police fired tear gas into a crowd that was divided by the newly erected cordon. 
 
 Many in the anti-Morsi camp accused the Muslim Brotherhood supporters who arrived Wednesday evening of inciting violence against peaceful protesters. Islam Hassan, a 26-year-old clothing-store manager, said he would stay at the site until Mr. Morsi rescinded his extraordinary powers. 
 
 On the other side of the cordon, a larger group of men who characterized themselves as Muslim Brotherhood supporters also said they would remain at the site. They characterized the anti-Morsi protesters as thugs paid by former regime insiders to bring down an elected leader. 
 
 "The problem is that these people could say no in the [Dec. 15 constitutional] referendum, but they don't want a referendum," said Morsi supporter Ahmed Abdel Khaleq, a 29-year-old accountant. "They don't want a democracy." 
 
 Early Thursday, hundreds of pro-Morsi protesters had spread blankets on the hard pavement in front of the palace, preparing to spend a night in the rough to hold their territory. Members of the pro-Morsi crowd were also seen pummeling and dragging a man they characterized as an opposition thug. 
 
 The administration of Mr. Morsi, who hasn't appeared in public since he left the presidential palace after protesters descended on Tuesday, has sent out confused messages about how the conflict could be resolved. His vice president, Mahmoud Mekki, in remarks to reporters Wednesday, offered to sit down and negotiate with the opposition. He later said the proposal was his own, not a formal government offer. He said the referendum on the constitution would go forward as planned. 
 
 As the crisis deepened, three of Mr. Morsi's aides, tapped from outside the Muslim Brotherhood, quit in protest. "Egypt is bigger than a narrow-minded elite," one of the aides, Seif Abdel Fattah, told Egyptian television. He added that he could "no longer stay silent because the Muslim Brotherhood had harmed the nation and the revolution." 
 
 —Sam Dagher in Cairo 
 
 and Stephen Fidler in Brussels contributed to this article. 
 
 Printed in The Wall Street Journal, page A1 ||||| Tens of thousands march to the presidential palace in Cairo, undeterred by riot police and tear gas. 
 
 CAIRO — Anger between Egypt’s rival political camps erupted into street battles Wednesday after Islamist supporters of President Mohamed Morsi tore down tents of anti-government demonstrators, raising the possibility of widening violence over the nation’s proposed constitution. 
 
 Pro-Morsi factions overran about 200 protesters camped outside the presidential palace in north Cairo. The clashes came after the Muslim Brotherhood’s Freedom and Justice Party called thousands of its members into the streets in a counter-demonstration to drive opposition movements from the presidential palace. 
 
 Shoving and punching spilled down a boulevard as hurled stones, swinging sticks and firebombs filled the dusk in one of the capital’s wealthiest neighborhoods. Pro-Morsi contingents, including Brotherhood followers and ultraconservative Salafis, chased opposition activists shouting: “God is great. The people support the president’s decision.” 
 
 More than 125 people were injured on a cityscape that had the charged air of a flourescent-lit battlefield with competing banners, bandaged men and dinner trays used as shields to block barrages of rocks. 
 
 Police were slow to react but eventually arrived and attempted to separate the two sides even as the skirmishes raised fears that animosity between Islamists and the mainly secular opposition were a dangerous foreshadowing. Both camps threatened to march against each other and there appeared little compromise in a battle over the nation’s future that symbolizes the larger struggle over political Islam rising from the Arab Spring. 
 
 “Vicious attack vs. peaceful protesters in front of presidential palace,” tweeted Mohamed ElBaradei, a Nobel Peace Prize laureate and opposition leader. “Regime leading Egypt into violence and bloodshed.” 
 
 The clashes revealed new cracks in Morsi’s government from officials disturbed by the power and meddling of the Brotherhood. Three presidential advisors resigned, including Seif Abdel-Fattah, who told the Egyptian media: “Egypt is bigger than a narrow-minded elite .... We can no longer stay silent because they [the Brotherhood] have harmed the nation and the revolution.” 
 
 Tensions began two weeks ago when Morsi, a former Brotherhood leader, issued a decree that expanded his powers and protected the Islamist-dominated constitutional assembly from judicial oversight. The country’s highest court was expected to dissolve the assembly but delegates quickly finished a draft constitution that Morsi ordered be put to a national referendum Dec. 15. 
 
 Opposition factions marched on the presidential palace Tuesday to protest Morsi’s authority and the charter, which they say would open the country to Islamic law and a scaling back of civil rights. The demonstration angered the Brotherhood, which on Saturday avoided confrontation with the opposition by holding a massive rally miles away from Tahrir Square, where anti-Morsi movements have made their base. 
 
 But the Brotherhood on Wednesday was more aggressive: “The president will not retreat, and if the state apparatus is weakened by the wounds of the previous period, then the people can impose their will and protect legitimacy,” said Essam Erian, deputy head of the Freedom and Justice Party. 
 
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 Special correspondent Gaser El Safty contributed to this report. ||||| Egyptian Army deploy near the presidential palace to secure the site of overnight clashes between supporters and opponents of President Mohammed Morsi in Cairo, Egypt, Thursday, Dec. 6, 2012. The Egyptian... (Associated Press) 
 
 The Egyptian army deployed tanks outside the presidential palace Thursday following fierce street battles between supporters and opponents of Mohammed Morsi that left five people dead and more than 600 injured in the worst outbreak of violence between the two sides since the Islamist leader's election. 
 
 The intensity of the overnight violence, with Morsi's Islamist backers and largely secular protesters lobbing firebombs and rocks at each other, signaled a turning point in the 2-week-old crisis over the president's assumption of near-absolute powers and the hurried adoption of a draft constitution. 
 
 Opposition activists defiantly called for another protest outside the palace later Thursday, raising the specter of more bloodshed as neither side showed willingness to back down. 
 
 Morsi was in the palace Thursday conducting business as usual, according to a presidential official who spoke on condition of anonymity because he was not authorized to address the media. 
 
 Egypt has seen sporadic clashes throughout nearly two years of political turmoil after the ouster of autocratic leader Hosni Mubarak. But Wednesday's street battles were the worst between Morsi's supporters and followers and came after an implicit call by the Muslim Brotherhood for its members to go to the palace and evict anti-Morsi protesters who had camped out there. 
 
 Unlike Mubarak, Morsi was elected in June after a narrow victory in Egypt's first free presidential elections, but many activists who supported him have jumped to the opposition after he issued decrees on Nov. 22 that put him above oversight and a draft charter was later rushed through by his Islamist allies despite a walkout by Christian and liberal factions. 
 
 Compounding Morsi's woes, four of his advisers resigned Wednesday, joining two other members of his 17-member advisory panel who have abandoned him since the crisis began. 
 
 Six tanks and two armored vehicles belonging to the Republican Guard, an elite unit tasked with protecting the president and his palaces, were stationed Thursday morning at roads leading to the palace in the upscale Cairo district of Heliopolis. The guard's commander, Maj. Gen. Mohammed Zaki, sought to assure Egyptians that his forces were not taking sides. 
 
 "They will not be a tool to crush protesters and no force will be used against Egyptians," he said in comments carried by the official MENA news agency. 
 
 The situation was calm Thursday morning, with thousands of Morsi supporters camping outside the palace after driving away opposition activists who had been staging a sit-in there, prompting fierce street battles that spread to residential areas. 
 
 "I don't want Morsi to back down," said Khaled Omar, a Brotherhood supporter. "We are not defending him, we are defending Islam, which is what people want." 
 
 Other Brotherhood supporters outside the palace accused opposition protesters of being Mubarak loyalists or foot soldiers in a coup attempt. 
 
 "They want to take over power in a coup. They are conspiring against Morsi and we want him to crack down on them," said one, Ezzedin Khoudir. "There must be arrests." 
 
 The violence began when the Brotherhood called on its members to head to the presidential palace to "defend legitimacy" and protect it against what a statement termed attempts by the opposition to impose its will by force. In response, thousands descended on the area, chasing away some 300 opposition protesters who had been staging a peaceful sit-in outside the palace's main gate. Clashes later ensued with the two sides using rocks, sticks and firebombs. 
 
 State television quoted the Health Ministry as saying Thursday that five people were killed and 644 injured by beatings, gunshot wounds and tear gas inhalation. 
 
 Morsi, meanwhile, seemed determined to press forward with plans for a Dec. 15 constitutional referendum to pass the new charter. The opposition, for its part, is refusing dialogue unless Morsi rescinds the decrees giving him near unrestricted powers and shelves the controversial draft constitution, which the president's Islamist allies rushed through last week in a marathon, all-night session shown live on state TV. 
 
 Mohamed ElBaradei, a leading opposition reform advocate, said late Wednesday that Morsi's rule was "no different" than Mubarak's. 
 
 "In fact, it is perhaps even worse," the Nobel Peace Prize laureate told a news conference after he accused the president's supporters of a "vicious and deliberate" attack on peaceful demonstrators outside the palace. 
 
 "Cancel the constitutional declarations, postpone the referendum, stop the bloodshed, and enter a direct dialogue with the national forces," he wrote on his Twitter account, addressing Morsi. 
 
 Wednesday's violence spread to other parts of the country. Anti-Morsi protesters stormed and set ablaze the Brotherhood offices in Suez and Ismailia, east of Cairo, and clashes broke out in the industrial city of Mahallah and the province of Menoufiyah in the Nile Delta north of the capital. 
 
 Rival demonstrations also were held outside the Brotherhood's headquarters in the Cairo suburb of Moqatam and security officials said senior Brotherhood official Sobhi Saleh was hospitalized in Alexandria after being severely beaten by Morsi opponents. Saleh, a former lawmaker, played a key role in drafting the disputed constitution. The officials spoke on condition of anonymity because they were not authorized to speak to the media.
– Violent protests in Cairo have reached a pitch not seen since the days of Egypt's recent revolution, the Wall Street Journal reports: Tens of thousands of demonstrators battled on the streets yesterday, with the AP reporting five dead and more than 600 injured as some threw rocks and Molotov cocktails. The Egyptian army deployed tanks outside the presidential palace today, as Mohamed Morsi conducted business as usual inside. The AP notes that all appeared calm this morning, with thousands of Morsi supporters camping outside the palace after driving away opposition activists. The fighting had centered around the palace, where police established a barrier between the groups. Supporters of Morsi stormed an encampment of 200 protesters, ripping down their tents, the Los Angeles Times reports. "The problem is that these people could say no" in an upcoming constitutional referendum, "but they don't want a referendum," said one Morsi backer. "They don't want a democracy." Meanwhile, three of Morsi's non-Brotherhood aides have quit: "Egypt is bigger than a narrow-minded elite," said Seif Abdel Fattah. "We can no longer stay silent because (the Brotherhood has) harmed the nation and the revolution."