Activists: 220 killed in latest Syria massacre Updated at 3:00 a.m. (CBS/AP) BEIRUT - Syrian activists reported a new massacre late Thursday in the central Hama province, claiming regime forces had killed more than 200 people in shelling followed by ground attacks in the central Hama province. The details of the incident have been impossible to confirm, given the Syrian government's ban on independent journalism, and while President Bashar Assad's regime acknowledged violence in the Tremseh area of Hama, it blamed the deaths on "terrorist" groups. A member of the Local Coordination Committees opposition group told CBS News late Thursday that Syrian army forces surrounded Tremseh in the morning and pounded the city with shelling and fire from aircraft. It began, according to the LCC, as a search for defected soldiers who had joined the rebel Free Syrian Army. The LCC and other groups claim that, after the initial bombardment, members of the government-backed "shabiha" militias stormed the city and executed dozens more. The LCC source who spoke to CBS News put the death toll at 220 - and said many of the bodies seen at the local mosque were those of army defectors who seemed to have been summarily executed. Syrian refugee children caught in crossfire Brutal rape claims against Syria forces Syria in crisis: The key players The Syrian Observatory for Human Rights, a U.K.-based opposition group, said it was aware of up to 100 killed from its sources on the ground, but the group had only been able to confirm the names of 30 people as of Thursday evening. The accounts given by the opposition groups echoed at least two previous reported massacres. In the town of Houla, 108 people were allegedly killed in a massacre at the end of May that the U.N. said was at least partially to blame on shabiha militiamen, and which international peace envoy Kofi Annan predicted would be a "tipping point" in the conflict. About two weeks after the Hama incident, however, an attack which opposition figures say followed the exact same pattern - shelling and bombardment followed by door-to-door executions by the shabiha - was seen in the nearby village of Qubeir. Activists say 78 people were killed in total. The government, again, blamed "terrorist groups." Opposition activists say more than 17,000 people have been killed since the uprising against Assad began in March 2011. The dictator has come under increasing pressure from the international community as the bloodshed continues, but as the conflict spirals further into a civil war, hopes for a peaceful transition to an interim or caretaker government are dimming. The latest report of violence came in the wake of the highest-level defection yet from Assad's regime - his ambassador to Iraq. Mortar fire reported in central Damascus Defected Syria envoy: Only force can topple Assad Syria's ambassador to Iraq abandons Assad A still from a Youtube video shows Nawaf al-Fares announcing his defection from Syrian President Bashar Assad's government.