BEIRUT — A government airstrike killed tens of people Sunday in a town near the central city of Hama, anti-regime activists in Syria said.

The attack came as the main international envoy was beginning talks in Damascus aimed at ending the civil war.

The Britain-based Syrian Observatory for Human Rights said “tens of people” were killed in a strike by a fighter jet on Halfaya on Sunday.

An amateur video released online Sunday shows people rushing toward a building an off-camera narrator says is a bakery. The bodies of about a dozen dead or seriously wounded people lie in the street, some of them in puddles of blood.

Rubble and dust cover another pile of bodies along the building’s wall. Residents and armed rebels carry the wounded away while others dig through the rubble looking for survivors.

It was unclear why Syrian forces targeted the town.

Activists and rights groups accuse the Syrian government of President Bashar Assad of taking revenge for victories by rebel forces on civilian populations who support them.

Rebels have been clashing with government forces in recent days in the region around Halfaya, some 15 miles northwest of Hama, most notably in the village of Morek. Activists say rebels have taken over a number of regime checkpoints there as part of an effort to control the country’s main north-south highway.

Syria’s crisis began in March 2011 with political protests and has since evolved into a civil war, with scores of rebel groups across the country battling Assad’s forces.

Activist say more than 40,000 people have been killed.

International diplomacy has failed to slow the crisis.

International envoy Lakhdar Brahimi was in Damascus Sunday to push for a negotiated solution to the conflict. Previous efforts have proved fruitless.