In this amateur video provided by a group which calls itself Ugarit News, Syrian rebels cross a road during a raid on the village of Hatla, Syria, Wednesday, June 12, 2013. On Wednesday, activists said Syrian rebels battled Shiites in Hatla, in the country's east, killing more than 60 people, including civilians. The content has been authenticated based on its translation and content has been checked by regional experts against known locations and events, and is consistent with independent Associated Press reporting. AP Photo/Amateur video via Ugarit News In this amateur video provided by a group which calls itself Ugarit News, Syrian rebels attend to one of their own who has been shot during a raid on the village of Hatla, Syria, Wednesday, June 12, 2013. FILE - This Wednesday, June 5, 2013 file photo released by the Syrian official news agency SANA, shows a damaged church in the town of Qusair, near the Lebanese border, in Homs province, Syria. BEIRUT (AP) - Syrian rebels, including Sunni extremists, stormed a village and battled pro-regime militiamen, killing more than 60 Shiite fighters and civilians in an attack steeped in the sectarian hatreds that increasingly characterize the civil war, activists said Wednesday. In the raid, which comes at a time when the West is worried that extremists are increasingly joining the rebellion, the victorious fighters raised black Sunni Islamist flags over the eastern village of Hatla. In amateur videos, the fighters - some wearing al-Qaida-style headbands - vented anti-Shiite slurs and fired in the air. "The homes of the infidel Shiites were burned," the voice behind the camera in one video shouted as smoke rose in the background from several houses. In another video, the fighters pulled blankets off corpses to show them off, one with a wound to the head. A gunman talking to the camera gloated, saying, "This is your end, dogs." The videos appeared genuine and conformed with other Associated Press reporting on the events depicted. The attack Tuesday on Hatla, in Syria's Deir el-Zour region near Iraq, underlined the increasingly sectarian nature of the conflict. The regime called it a "massacre," and some opposition members expressed concern about the nature of the attack. The U.S. and other Western nations have been hesitant to arm the outgunned and outmanned rebels because of Sunni jihadi radicals among their ranks. State Department spokesman Jen Psaki said the U.S. was "appalled by reports that rebels have killed 60 Shia in Hatla village." "The motivations and circumstances surrounding this massacre remain unclear, but the United States strongly condemns any and all attacks against civilians," Psaki said. The uprising began more than two years ago with peaceful protests against President Bashar Assad but later grew into a civil war that has killed more than 80,000 people. Most of the armed rebels in Syria are from the country's Sunni majority, while Assad has retained core support among the minorities, including his own Alawite sect, an offshoot of Shiite Islam, along with Christians and Shiites. In the past year, sectarian bitterness has grown in the conflict. Each sect has been accused of massacres against the other, and Sunni and Shiite fighters from other countries have increasingly joined the battle. But the sense of the fight being a battle between faiths was taken up a notch after Shiite guerrillas from Lebanon's Hezbollah helped Assad's forces take the rebel stronghold of Qusair last week. Some fighters in Hatla can be heard in the video calling the attack "the first revenge for Qusair." An activist based in Deir el-Zour said the rebel attack was in retaliation for an attack Monday by Shiites from Hatla that killed four rebels. The town is home to several thousand people, about 30 percent of them Shiites, and was considered a pro-regime community in the Euphrates River valley, where rebels - including the al-Qaida-linked group Jabhat el-Nusra - have taken over much of the territory. Rebels launched a counterattack Tuesday, said the activist, Thaer al-Deiry, who identified himself only by his nickname for fear of government retaliation, via Skype. He said some 150 Shiites from the village fled across the Euphrates to the government-held village of Jafra. Activists said many of the dead were pro-government militiamen who had earlier attacked the rebel bases. But there were also many civilians killed in the raid, according to the Syrian Observatory for Human Rights, a British-based anti-Assad group that has a large network of activists. "These atrocities were carried out on a sectarian basis," the Observatory said, adding that it was difficult to discern the fighters from the civilian casualties. The group posted two videos from the scene. More people were believed killed in the fighting, including many children and civilians, according to an opposition figure who was informed of details of the attack. A Shiite mosque in the village was also set on fire, he said, speaking on condition of anonymity because he feared retaliation. The Observatory said thousands of rebels took part in the attack, and at least 10 were killed. A Facebook page of Islamist activists in Deir el-Zour province said Jabhat el-Nusra and rebel fighters from the Free Syrian Army, the main rebel umbrella group, were involved. There was no immediate confirmation from the group, which includes many non-Syrian jihadists. In the videos, Sunni extremists among the fighters were seen moving through streets that appeared vacant, cheering and insulting Shiites, whom they consider infidels and a breakaway sect from Islam. "The flag of 'There is no god but God' was raised over the homes of the infidel Shiites," a voice rang out, referring to the black banners used by jihadists around the region, as others fired in the air in celebration. "The mujahedeen are celebrating entering the homes of the rejectionists," a reference to Shiites. One fighter then addresses the camera, accusing Shiites in the Gulf state of Kuwait of financing the Shiite fighters from the village. "People of Kuwait, Sunni people of Kuwait, you will be held responsible if you don't kill the Shiites in your country," the fighter, with a black al-Qaida type headband, said, explaining that signs of Shiite Kuwaiti funds were found in the village. Help your religion, not necessarily the Syrian people. In a video of a Sunni Kuwaiti cleric, Shafi al-Ajmi, hails the fall of Hatla and promises that other Shiite villages in the northern province of Aleppo will follow. "Today we took Hatla village and we slaughtered its religious leader," he tells a cheering crowd that raised banners calling for the expulsion of the Lebanese ambassador. He was apparently speaking in Kuwait. Like you slaughtered our women and children in Qusair, we slaughtered one of your symbols ... and his son. A pro-Hezbollah Facebook page said the Shiite cleric was missing. Each side has been accused of mass killings. Last month, Alawite fighters were blamed for killing dozens of civilians in two Sunni towns in western Syria, part of what rebels call an attempt by Alawites to clear their coastal heartland of Sunni communities. In the videos from Hatla, some fighters also refer to the attack as revenge from those two Sunni towns. Radwan Ziadeh, a leading Syrian opposition figure in exile, described the attack on Hatla as a "dangerous development" triggered by Hezbollah's intervention in Syria. It also shows that the revolution is taking a sectarian angle. This will have effects on the long-term not only in Syria but also in Lebanon. There are dangers that that the fanatics from both sides, Shiite and Sunni will have the upper hand," Ziadeh said. In the latest instance of Syria's violence spilling over its borders, a Syrian government helicopter fired at least two missiles at the border town of Arsal in Lebanon, officials and residents said. The town is predominantly Sunni Muslim, and support for the Syrian rebels runs high. Scores of rebels and civilians who fled from Qusair have taken refuge there. Lebanon's President Michel Suleiman said the rockets were a "violation of Lebanon's sovereignty." A statement issued by the Syrian military said Syria "respects Lebanese sovereignty," adding that a Syrian army helicopter was chasing armed groups some of whom fled to Lebanese territory. Building on its victory in Qusair, the Syrian military has shifted its attention to try to clear rebel-held areas in the province of Homs, a linchpin area linking Damascus with regime strongholds on the Mediterranean coast, and the northern city of Aleppo. On Wednesday, the Observatory reported heavy clashes in the center of Homs city, mostly in the neighborhood of Wadi Sayeh. The fighting appeared to be an attempt by government forces to separate two main rebel-held areas in the city, Khaldiyeh and the city center. The state-run news agency SANA said troops killed several gunmen in the town of Talbiseh north of Homs. The Observatory reported fighting and shelling in the northern Damascus neighborhood of Barzeh, which has witnessed clashes between troops and rebels over the past weeks. It said there were casualties without giving figures. Associated Press writers Albert Aji in Damascus, Syria, Bassem Mroue in Beirut, and Matthew Lee in Washington contributed to this report.