Palestinians celebrate 'lone-wolf' attack on Jerusalem synagogue The brutal killings of five worshippers - including three Americans - in a Jerusalem synagogue Tuesday by two Palestinians wielding meat cleavers and a gun appears to be a lone-wolf attack, Israel's national police commissioner says. The violence was met with celebration from Palestinians, as revelers in the Gazan city of Rafah handed out candy and brandished axes and posters of the suspects in praise of the deadly attack, according to the Jerusalem Post. Hamas-affiliated social media also circulated violent and anti-Semitic cartoons hailing the killings. National Police Commissioner Yochanan Danino told the newspaper that a preliminary investigation of the attack indicates a grassroots, independent effort. Hamas said the attack was motivated by revenge after a Palestinian bus driver was found hanged in his vehicle earlier in the week, and called for more violence. But Israeli police believe Youssef al-Ramouni, 32, who was found dead at the start of his bus route on Sunday, committed suicide, according to the Jerusalem Post. The American citizens killed Tuesday -- identified by the State Department as Mosheh Twersky, Aryeh Kupinsky and Cary William Levine -- were killed along with a Briton when the assailants, identified as cousins, stormed the building during morning prayers and began attacking people. Police said those killed were all immigrants to Israel and held dual citizenship. Twersky, the grandson of a renowned rabbi from Boston, Joseph Soloveichik, was the head of Yeshivas Toras Moshe, a religious seminary for English-speaking students. The Briton was identified as 68-year-old rabbi Avraham Shmuel Goldberg, from London, The Telegraph reports. Eight people were injured -- one critically, who later died -- before the attackers were killed in a shootout with police. The Times of Israel cited witnesses who said the attackers stormed the synagogue, in the ultra-Orthodox Har Nof neighborhood in the western part of Jerusalem, shouting "Allahu Akbar," Arabic for "God is Great," and creating a horrific scene of bloody carnage. I tried to escape. The man with the knife approached me. There was a chair and table between us ... my prayer shawl got caught. I left it there and escaped," a man who identified himself as Yossi, who was praying at the synagogue at the time of the attack, told Israeli Channel 2 TV. He declined to give his last name. The attack was the deadliest in Israel's capital since 2008, when a Palestinian gunman shot eight people in a religious seminary school. Netanyahu vowed that Israel will "respond harshly" to the attack, which he denounced as a "cruel murder of Jews who came to pray and were killed by despicable murderers." U.S. Secretary of State John Kerry said he spoke to Netanyahu after the assault and denounced it as an "act of pure terror and senseless brutality and violence." Kerry blamed the attack on Palestinian calls for "days of rage," and said Palestinian leaders must take serious steps to refrain from such incitement. He also urged Palestinian leaders to condemn the attack "in the most powerful terms." Hours after Kerry spoke, Palestinian Authority President Mahmoud Abbas condemned the attack, the first time he has done so since a recent spike in deadly violence against Israelis began. He also called for an end to Israeli "provocations" surrounding the sacred site. In a statement, Abbas' office said he "condemns the killing of the worshippers in a synagogue in west Jerusalem." The statement called for an end to the "invasion" of the mosque at a contested holy site in the city and a halt to "incitement" by Israeli ministers. But Hamas, the militant group that runs the Gaza Strip, praised the attack as retaliation for what it claimed was the murder of a Palestinian bus driver who was found hanged in his vehicle late Sunday. Israeli police, citing autopsy results, have classified the man's death as a suicide, but that has not been accepted by the man's family. President Barack Obama said there "can be no justification for such attacks against innocent civilians." "The thoughts and prayers of the American people are with the victims and families of all those who were killed and injured in this horrific attack and in other recent violence," Obama added in a statement Tuesday. Israeli police spokeswoman Luba Samri said the attackers were cousins from East Jerusalem, which has been the scene of relentless clashes between Israeli police and Palestinian protesters in recent months. She identified the assailants as Ghassan and Oday Abu Jamal from the Jabal Mukaber neighborhood. The Popular Front for the Liberation of Palestine, a militant group, said the cousins were members. A PFLP statement did not specify whether the group instructed the cousins to carry out the attack. Soon after the attack, clashes broke out outside the Abu Jamals' home, where dozens of police had converged. Residents hurled stones at police who responded using riot dispersal weapons. Residents in the neighborhood, speaking on condition of anonymity for fears for their own safety, said 14 members of the Abu Jamal family were arrested. Mohammed Zahaikeh, a social activist in Jabal Mukaber, said one of the relatives of the cousins, Jamal Abu Jamal, was released in a 2011 prisoner swap and re-arrested recently by Israeli police. Netanyahu has ordered authorities to destroy the homes of the attackers and Palestinians involved in other recent deadly attacks. Netanyahu announced the directive Tuesday after a meeting with top security officials. He did not say when the demolitions would take place. Police spokesman Micky Rosenfeld said two police officers were among the eight wounded, four of whom were reported in serious condition. He said police were searching the area for other suspects. Associated Press footage from the scene showed the synagogue surrounded by police and rescue workers following the attack. Wounded worshippers were being assisted by paramedics and a bloodied meat cleaver lay near the scene of the attack. Initially, police had described the weapons used as knives and axes. Another witness, identified only as Zohar described panic at the scene. "I heard shooting and one of the worshipers came out covered in blood and shouted 'There's a massacre,'" he told The Times of Israel. A photo in Israeli media from inside the synagogue showed what appeared to be a body on the floor draped in a prayer shawl, with blood spattered nearby. Yosef Posternak, who was at the synagogue at the time of the attack, told Israel Radio that about 25 worshippers were inside when the attackers entered. I saw people lying on the floor, blood everywhere. People were trying to fight with [the attackers] but they didn't have much of a chance," he said. Jerusalem has seen a spate of attacks by Palestinians against Israelis, most of which have involved cars being driven into pedestrians. At least six people had been killed in Jerusalem, the West Bank and Tel Aviv prior to Tuesday. Jerusalem residents have already been fearful of what appeared to be lone-wolf attacks, but Tuesday's early morning attack on a synagogue harks to the gruesome attacks during the Palestinian uprising of the last decade. Israel's police chief said Tuesday's attack was likely not organized by militant groups, similar to other recent incidents, making it more difficult for security forces to prevent the violence. These are individuals that decide to do horrible acts. It's very hard to know ahead of time about every such incident," Yohanan Danino told reporters at the scene. Tensions appeared to have been somewhat defused last week following a meeting between Netanyahu, U.S. Secretary of State John Kerry and Jordan's King Abdullah II in Jordan. The meeting was an attempt to restore calm after months of violent confrontations, with Israel and the Palestinians saying they would take steps to reduce tensions that might lead to an escalation. The Jerusalem holy site is referred to by Jews as the Temple Mount because of the Jewish temples that stood there in biblical times. It is the most sacred place in Judaism; Muslims refer to it as the Noble Sanctuary, and it is their third holiest site, after Mecca and Medina in Saudi Arabia. The site is so holy that Jews have traditionally refrained from going there, instead praying at the adjacent Western Wall. Israel's chief rabbis have urged people not to ascend to the area, but in recent years, a small but growing number of Jews, including ultranationalist lawmakers, have begun regularly visiting the site. Click for more from The Times of Israel.