Opposition activists say Syrian warplanes bombed targets near Damascus on Friday, a day after an explosion in the capital left at least nine people dead.

The Britain-based Syrian Observatory for Human Rights says government shelling is underway in areas including Douma, a rebel stronghold.

The state-run SANA news news agency says “terrorists” detonated explosives at a gas station in a Damascus neighborhood, on Thursday.

There was no immediate claim of responsibility.

Civil war between rebels and the Assad government has gripped Syria since evolving from peaceful anti-government protests in March 2011.

The United Nations estimates 60,000 people have died in Syrian fighting, a figure that surpasses opposition estimates by about one-third.