Syrian rebels stormed a government intelligence complex in the oil-rich east of the country on Tuesday, freeing at least 11 people held in a prison at the facility, activists said.

After five days of heavy clashes around the intelligence compound in the city of Deir el-Zour, rebels finally overran the complex early Tuesday following intense fighting overnight, the Britain-based Syrian Observatory for Human Rights said. Opposition figures were reportedly being held at the jail on the complex's grounds, but it was not immediately clear whether those freed Tuesday are fighters or activists.

Government forces responded to the rebel advance by unleashing a series of airstrikes on the compound, trying to push the opposition fighters from the facility.

Deir el-Zour has been the scene of heavy fighting since the uprising against Syrian President Bashar Assad began in March 2011. The province, which goes by the same name as the city, is located along Syria's border with Iraq and includes several oil installations that the rebels have repeatedly targeted.

The aid group Doctors Without Borders said last month that government forces are shelling and bombing Deir el-Zour almost daily. It said tens of thousands of Syrians, many of them wounded, remain trapped in the city.

Also Tuesday, regime warplanes also carried several airstrikes on rebel positions in restive towns and villages around Damascus, including eastern Ghouta and Yalda, and hit other suburbs with artillery, the Observatory said. The group relies on the reports from activists on the ground.

After capturing several major army bases and government outposts, the rebels control large swathes of land in northeastern Syria. Assad's troops, however, continue to hold a tight grip on the capital after nearly two years of conflict.

The areas on the capital's doorstep have been rebel strongholds since early on in the revolt. In recent months, the rebels have used them as a base from which they have been trying to push into central Damascus, the seat of Assad's power.