World Bulletin / News Desk

At least 28 civilians were killed in heavy bombardment of a besieged Syrian opposition stronghold, including near a school, east of Damascus on Sunday, a monitoring group said.

According to the Syrian Observatory for Human Rights, rockets fired by regime forces rained down on Douma, one of the largest towns in the opposition-held Eastern Ghouta region. 

Observatory head Rami Abdel Rahman said air strikes also hit Douma and the nearby town of Saqba, but it was unclear whether they were carried out by Syrian or Russian warplanes.

The air strikes and rockets wounded dozens, he said.

"One of the air strikes on Douma hit near a school, killing the school's principal," Abdel Rahman said.

Government forces regularly bombard Eastern Ghouta, and opposition there fire rockets and mortar shells into the capital.

On Sunday, a young girl was killed and three people were wounded in opposition mortar fire on Damascus, according to the national news agency SANA.

Last month, regime forces and opposition groups tried to reach a 15-day ceasefire in Eastern Ghouta, but the talks failed and violence has resumed.

A local activist group in Douma shared photographs on Facebook of crumbling buildings and bloodied children lying in a makeshift clinic.