Rebel activists reported upwards of 400 people were killed in Syria over Saturday, including a massacre in a Sunni town south of the capital, as the war-torn country saw one of its bloodiest periods since the beginning of the uprising 17 months ago.

A local activist in the town of Daraya told Reuters that 200 bodies had been found there, most of them shot execution style.

“In the last hour, 122 bodies were discovered and it appears that two dozen died from sniper fire and the rest were summarily executed by gunshots from close range,” the activist told Reuters by telephone.

He called what happened “a massacre.”

The Local Coordination Committees reported that 310 people had been killed in and around Damascus and another 130 in fighting in other places around the country, including Aleppo, Daraa and Deir Al Zour in the north of the country.

State-run media reported government forces “cleared the area of terrorists,” their term for the rebels, “and eliminated a large number of them.”

Video from the town posted on YouTube showed scores of bodies with gunshot wounds lying in a dark room. Warning: graphic footage

Another video from the town purported to show forces loyal to Assad beating bound rebels.

Damascus itself also saw heavy fighting on Saturday, as tanks shelled rebel-held neighborhoods in the south of the city, Reuters reported.

On Friday, Damascus residents reported hearing loud explosions as shells fired from the Qasioun mountains overlooking the capital slammed into Daraya and the nearby suburb of Moadimiyeh.

Human rights groups say more than 20,000 people have been killed in Syria since the uprising against Assad erupted in March 2011 and evolved into a civil war. The bloodshed already has spilled over into neighboring countries.

On Friday, the United Nation’s refugee body reported that the number of people fleeing the country had surpassed 200,000, as thousands headed for safe havens in Turkey and Jordan.