At least 31 people, most of them civilians, have been killed in a powerful car bomb targeting the ruling Baath Party headquarters in central Damascus on Thursday, activists said.
The official SANA news agency also reported the blast in the central Mazraa neighbourhood on Thursday, saying a “large number” of civilians were killed or wounded in what it described as a “terrorist attack”.
It did not say what caused the explosions.
The pro-regime TV station Al-Ikhbariya showed images of what appeared to be at least four dead bodies on the ground and cars on fire.
The footage shows firefighters trying to douse cars on fire and lifeless bodies lying on the grass of a public garden.
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.
Al Jazeera’s Rula Amin, reporting from Beirut in neighbouring Lebanon, said the explosion took place in a heavily fortified area.
“The city is under very strict restrictions. People who have come out of Damascus have been telling us about how many checkpoints are there within the city limits, inside the neighbourhoods and between different areas; especially around the headquarters of the Baath Party, the security installations and the presidential palace,” Amin said.
“So it seems that whoever was behind the attack had managed to go through many checkpoints until they got to the point where they can explode the car.”
The explosion comes amid reports of fierce clashes over the past few days between the opposition and regime forces around Damascus, as rebels tried to make advances in the city.
The car bombing was followed soon after by a mortar attack on a military headquarters, both government-sponsored media and opposition activists reported, without giving information on casualties.
A security official reported another blast the capital’s northeastern Barzeh neighbourhood. He had no other information and spoke on condition of anonymity because he was not authorised to brief the media.
Thursday’s blasts 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.
Damascus has so far mostly avoided the large-scale violence that has destroyed other Syrian cities, though deadly car bombings have targeted government buildings in the capital.
The latest development came as a major opposition meeting was underway in Cairo, the Egyptian capital.
In a communique drafted for Thursday’s meeting, the opposition Syrian National Coalition said it was willing to negotiate a peace deal to end the conflict in Syria but that Assad cannot be a party to any settlement.
The document, seen by Reuters news agency, said Assad and his cohorts must be held accountable for bloodshed and that any peace deal must be under the auspices of the US and Russia.