At least 21 dead in Damascus as Syrian forces, rebels trade salvos

DAMASCUS — Syrian government forces and rebel forces traded salvos of rockets and mortar shells Thursday around Damascus, killing at least 21 people in tit-for-tat violence.

Outside observers said anti-government forces struck first, after a rebel commander vowed to hit government-held areas of the Syrian capital to avenge the past week's strikes by government warplanes on opposition-held suburbs. That commander, Zahran Alloush of the Army of Islam rebel group, said in a tweet that his forces would keep firing mortars and rockets "until the capital is cleansed".

The state-run SANA news agency reported that at least five people were killed in the rebels' barrage. The British-based Syrian Observatory for Human Rights put the death toll higher at nine, and said rebels fired at least 60 mortar shells towards the city.

Later, government batteries rained shells and rockets on to rebel-held districts outside the city, including the suburb of Douma, a power base for the Army of Islam. Government forces have targeted that area heavily over the past week, including the use of barrel-sized bombs that are dumped from helicopters.

The observatory monitoring group said at least 16 people were killed in Thursday's government counterattack.

An activist in Douma, Hassan Taqulden, said the town suffered at least 38 hits from mortar shells or aircraft munitions.

"This is the worst we've seen," he said.

Gray smoke billowed from several parts of Damascus, and the thud of shells and wailing ambulance sirens pierced the morning calm. Damascus residents, terrified by the intensity of the barrage, kept mostly indoors.

Videos uploaded to social networks showed large columns of smoke rising, at least two wounded children weeping and a smashed ambulance.

The videos appeared genuine and corresponded to The Associated Press reporting of the event.

"Her family is dead," said an unidentified man in one video as the camera focused on a bloodied child.

The United Nations estimates that more than 220,000 people have been killed in Syria's nearly 4-year-old conflict.