A car bomb shook central Damascus on Thursday, exploding near the headquarters of the ruling Baath party and the Russian Embassy, eyewitnesses and opposition activists said. TV footage of the scene showed at least four lifeless bodies. Syrian state TV said 53 people were killed and more than 200 wounded in a car bomb attack near the headquarters of the ruling Baath party in central Damascus.

The Britain-based activist group the Syrian Observatory for Human Rights said most of the dead were civilians. Syrian state TV also reported the blast in the central Mazraa neighborhood, calling it a “terrorist” attack on a heavily populated area. It did not say what caused the explosion but reported that there were casualties and that the wounded included four children.

The pro-regime TV station Al-Ikhbariya showed images firefighters trying to douse burning cars, and lifeless bodies strewn on the grass of a public garden.

Syria’s pro-government Adunya TV reported that at least three other explosions hit Damascus, including two in the northern neighborhood of Barzeh, and that dozens of civilians were killed.

Eyewitnesses at the scene said a car had exploded at a security checkpoint between the Russian Embassy and the central headquarters of the ruling Baath party of President Bashar Assad.

Ambulances rushed to the scene of the blast, which also shattered windows and sent up a huge cloud of smoke visible throughout much of the city, eyewitnesses said.

“It was huge, everything in the shop turned upside down,” one local resident said, speaking on condition of anonymity for fear of retribution for speaking with foreign media.

Damascus has so far mostly been spared the large-scale violence that has destroyed other Syrian cities, though deadly car bombings have targeted government buildings in the capital.

First responders working after a huge explosion that shook central Damascus, Syria, Thursday, Feb. 21, 2013 (photo credit: (AP/SANA)

First responders working after a huge explosion that shook central Damascus, Syria, Thursday, Feb. 21, 2013 (photo credit: (AP/SANA)

The blast followed two mortar attacks in as many days on the capital. On Wednesday, two mortar shells exploded near a soccer stadium in Damascus, killing one player. The day before, two mortar shells went off near one of Assad’s three palaces in the city, causing only material damage.

Not long after the first blast Thursday, a security official reported a second blast in the capital’s northeastern Barzeh neighborhood. He had no other information and spoke on condition of anonymity because he was not authorized to brief the media.

The Britain-based Syrian Observatory for Human Rights said two car bombs had exploded near security centers in Barzeh. It gave no further details.

Mortar rounds reportedly exploded near the Syrian Army General Command in a separate incident.

Syria’s conflict began in March 2011 with political protests against the government and has since evolved into a civil war between Assad’s regime and hundreds of rebel groups seeking to topple it. The U.N. says some 70,000 people have been killed in the conflict so far.