The Somali armed group al-Shabab has launched an attack on the country's intelligence headquarters in central Mogadishu, setting off a bomb and opening fire on the complex, police and witnesses said.

The car bomb explosion, was followed by a fierce exchange of gunfire killing at least seven rebel fighters, officials said on Sunday.

There were no details on casualties among the security forces.

A spokesperson of the armed group confirmed with Al Jazeera that its fighters were involved in the attack and that they had entered the building.