In this Wednesday, Sept. 4, 2013 image taken from video obtained from the Shaam News Network, which has been authenticated based on its contents and other AP reporting, a Free Syrian army fighter during clashes with government forces, unseen, in Maaloula, western Syria. Syrian government troops battled al-Qaida-linked rebels over a regime-held Christian village in western Syria for the second day Thursday, as world leaders gathered in Russia for an economic summit expected to be overshadowed by the prospect of U.S.-led strikes against the Damascus regime. Residents of Maaloula said the militants entered the village late Wednesday, Sept. FILE - In this Wednesday, Sept. 13, 2006 file photo, thousands of Syrians, most of them Christians, celebrate the Christian Day of the Cross, by setting a fire on top of a mountain in the village of Maaloula, north of Damascus. AP Photo Bassem Tellawi, File FILE - In this Sunday, April 27, 2008 file photo, Syrian President Bashar Assad, center, and his wife Asma Assad, centre left, eat with Christian orphans at Saint Takla Convent in Maaloula some 60 km northern Damascus, Syria. AP Photo/Bassem Tellawi, File FILE - In this Sunday, Dec. 14, 2008 file photo, Syrian President Bashar Assad, left, and former U.S. President Jimmy Carter are seen in the split mountain in the mountainous town of Maíaloula, Arabic for entryway, some 56 kilometers to the northeast of Damascus, Syria. DAMASCUS, Syria (AP) - The sound of artillery reverberated Thursday through a predominantly Christian village north of Damascus as government troops and al-Qaida-linked rebels battled for control of the mountainside sanctuary. The hit-and-run attacks on the ancient village of Maaloula, one of the few places in the world where residents still speak Aramaic, highlighted fears among Syria's religious minorities about the growing role of extremists among those fighting in the civil war to topple President Bashar Assad's regime. The fighting came as President Barack Obama's administration pressed the U.S. Congress for its authorization of a military strike against the Assad regime, while the president arrived at a G-20 summit in Russia expected to be overshadowed by Syria. The fighting in Maaloula, a scenic village of about 3,300 perched high in the mountains, began early Wednesday when militants from Jabhat al-Nusra stormed in after a suicide bomber struck an army checkpoint guarding the entrance. The group - listed as a terrorist organization by the U.S. State Department - is one of the most effective fighting forces among Syrian rebels. The suicide attack triggered battles that terrorized residents in the village, famous for two of the oldest surviving monasteries in Syria - Mar Sarkis and Mar Takla. Online video showed rebels in the streets, some firing truck-mounted heavy machine guns in the direction of the surrounding mountains. The video appeared authentic and matched Associated Press reporting on the fighting. Residents said Wednesday the rebels took over the mountaintop Safir hotel and were firing in the direction of the community below. Rami Abdul-Rahman, director of the Britain-based Syrian Observatory for Human Rights, said that despite a heavy army presence in the village, the rebels staged hit-and-run attacks, at one point patrolling the streets on foot and in vehicles, and briefly surrounding a church and a mosque before leaving early Thursday. Heavy fighting around the village, which is on a UNESCO list of tentative world heritage sites - continued throughout the day, and heavy artillery echoed in the village. "The stones are shaking," said a nun at the Mar Takla monastery. We don't know if the rebels have left or not, nobody dares go out. Frightened residents expected the militants to return to the Safir hotel, she said, adding: "It's their home now." She spoke with the AP on condition of anonymity for fear of reprisals. Al-Mayadeen TV, a Lebanese station who has an embed with the Syrian army, broadcast live images from the area Thursday evening that showed smoke rising from behind the hotel, suggesting the military was shelling it. The nun said about 100 people from the village took refuge in the St. Takla convent that she helps run. The 27 orphans who live there had been taken to nearby caves overnight "so they were not scared," she said. Maaloula, about 40 miles (60 kilometers) northeast of Damascus, had been firmly under the regime's grip, despite sitting in the middle of rebel-held territory east and north of the capital. The village was a major tourist attraction before the civil war. Some of its residents still speak a version of Aramaic, the language of biblical times believed to have been used by Jesus. In 2008, Assad and his wife, Asma, visited the St. Takla convent, eating with Christian orphans there. In the same year, Assad took former U.S. President Jimmy Carter for a stroll in the area. The attack highlights fears among Syrian Christians that the alternative to Assad's regime, made up mostly of Alawites - followers of an offshoot of Shiite Islam - would not tolerate minority religions. The nun who spoke to AP said there were reports that the militants threatened villagers with death if they did not convert. The report could not be independently confirmed. Such fears have allowed Assad to retain the support of large sections among Syria's minorities, which includes Christians, Alawites, Druze and ethnic Kurds, throughout the 2½ year civil war. Most of the rebels and their supporters are Sunni Muslims. Elsewhere Thursday, a car bomb exploded outside a research center belonging to the Ministry of Industry in the area of Soumariya near Damascus, killing four people and wounding several others, a government official said. The official who spoke on condition of anonymity because he was not authorized to talk to reporters. Three people were wounded when mortar shells hit two residential neighborhoods of Damascus, the state news agency SANA reported. In the northern province of Aleppo, a Syrian surgeon working for an international aid group was killed. Doctors Without Borders said the 28-year-old surgeon, Muhammad Abyad, died in an attack. Abyad, whose body was found Tuesday, had been working in an Aleppo hospital run by the group. The conflict started in March 2011 as largely peaceful demonstrations against Assad's rule. Two years of fighting have led to a stalemate, with the rebels controlling much of the countryside in the north, east and south, and the regime holding most urban centers in the west, where the majority of Syrians live. More than 100,000 people have been killed, with nearly 7 million people uprooted from their homes. U.N. officials estimate that 5 million have been displaced inside the country while another 2 million have fled to neighboring countries. The total amounts to nearly a third of Syria's population, which was 23 million before the fighting began. U.N. humanitarian chief Valerie Amos met with Syrian government officials in the capital, lobbying for access to civilians trapped in areas where fighting has raged. After meeting with the president of the Syrian Arab Red Crescent, Amos told the AP that she is "extremely concerned that the situation on the ground is becoming worse." An alleged chemical attack near Damascus in August has brought the U.S. to the brink of launching punitive airstrikes after the Obama administration concluded that Assad's forces were responsible. Obama has been lobbying for international and domestic support for punishing the regime, which the U.S. says fired rockets loaded with the nerve agent sarin on rebel-held areas near Damascus before dawn Aug. 21, killing hundreds of people. Top administration officials have argued before the U.S. Senate and around the world that Assad would take inaction by Washington as a license for further brutality against his people. At the Group of 20 economic summit in St. Petersburg, Obama will confront Syria's closest supporter, Russia, as well as foreign leaders skeptical of his call for an international military intervention in Syria. Moscow and Washington have sharply disagreed over ways to end the bloodshed, with Russia protecting the Assad regime from punitive actions in the United Nations. The U.S. has backed the opposition and repeatedly has called on Assad to step down. Russia's Foreign Ministry said Syrian Foreign Minster Walid al-Moallem will travel to Moscow on Monday for a meeting with his Russian counterpart. European Union President Herman Van Rompuy urged U.N. investigators to release information as soon as possible about the purported chemical weapons attack Aug. 21 so that the international community can decide how to respond. SANA said Syrian Parliament speaker Jihad Laham sent a letter to the President of the European parliament, Martin Schulz, inviting members to visit Syria to follow up on the outcome of the U.N. investigation and help develop terms of reference for any subsequent investigations. Karam reported from Beirut. Associated Press writers Barbara Surk in Beirut contributed to this report.