A car bomb targeting the headquarters of Syria's ruling party killed 53 people in central Damascus on Thursday, opposition activists and state-run media said.

The explosion was close to a Russian Embassy building complex. No one there was injured or killed, but there was damage to a building, Russia's Foreign Ministry said.

Most of the victims were civilians. It's unclear who is behind the blast.

The explosion wounded more than 230 more people and burned 17 cars, Syrian state TV said.