More than 305 people were killed in Syria Wednesday, including at least 199 civilians, as the war-sundered country saw its bloodiest day yet in 18 months of civil war, a Britian-based rebel-linked group said Thursday.

The death toll included at least 55 people killed in Damascus suburbs and dozens more in other cities around the country, including 23 in Deir El Zour.

The Syrian Observatory for Human Rights said 40 civilians had been shot in al-Dhiyabia, near Damascus. Other activists put the death toll in the town as high as 107, Reuters reported.

“This is the highest toll in a single day since March 2011. And this is only counting those whose names have been documented. If we count the unidentified bodies, the figure will be much higher,” Observatory director Rami Abdel Rahman said to AFP.

Also on Wednesday, 14 regime troops were killed when rebels blew up a military command building in Damascus and in an ensuing gunbattle. The bombing was seen as a major strike against the heart of Assad’s embattled power base.

Some 30,000 people have been killed in Syria since the beginning of the uprising as rebel groups have battled troops loyal to President Bashar Assad for control of the country.

Wednesday’s daily death toll was the highest since violence broke out in March 2011. On July 19, some 302 people were reported killed in battles across the country.

High daily death tolls of two or more figures have become more common in the past several months as Assad has taken to using air power to fight the rebels and the revolutionaries have become supplied with more advanced arms.

Speaking to the United Nations on Wednesday, Egyptian President Mohammed Morsi termed the Syrian civil war the “tragedy of the age,” and called for its end.