An air strike on a rebel-held town southwest of the Syrian capital Damascus killed 20 people on Monday, January 14, resident opposition activists said, according to Reuters.

An activist living in Moadamiyeh, who asked not to be named, said the dead were members of two families and included women and children. Activist video footage showed images of the limp body of a boy being pulled out from broken concrete, his back covered in dust and his front in blood.

The Syrian Observatory for Human Rights, a monitoring group based in Britain, said it had the names of six children killed when a building hit by the strike collapsed.

The opposition-linked body said at least 10 people had been killed, but that the toll was likely to rise as many of the wounded were in critical condition and some civilians were still under the rubble.

On Sunday, forces loyal to President Bashar al-Assad killed at least 36 people, 14 of them children, in bombardments of rebel-held eastern areas near the capital, activists said.

The air, rocket and artillery campaign is the heaviest since rebels overran a helicopter base and missile base near Damascus two months ago and encroached on the main international airport, inching steadily closer to the capital, the sources said.

The military uses air strikes and artillery to hit rebels holding a line of eastern and southern areas around the capital.

More than 60,000 people have been killed during the 21-month-old revolt, which began with peaceful protests but turned violent after Assad's forces shot at demonstrators.