Islamic insurgents have fired mortar rounds on the presidential palace the Somali capital, and witnesses say at least 13 people have been killed in heavy fighting.

Prime Minister Nur Hassan Hussein was in the palace at the time of the attack. But government spokesman Abdi Haji Gobdon said no one in the palace was hurt.

Government forces retaliated, hitting a crowded Mogadishu market and a nearby residential area.

Ali Muse said he counted at least 11 bodies as the ambulance service he coordinates transported wounded people from the scene Monday. Aden Ibrahim said he counted two bodies from fighting in a separate attack elsewhere in Mogadishu.

Somalia has not had an effective government in 18 years.