Islamist insurgents killed 11 Burundi soldiers in Somalia's capital Mogadishu todday in the deadliest attack on an African Union peacekeeping force, Reuters reported. The African Union said a compound housing troops from Burundi had been targeted by mortar bombs. Islamist insurgents said two suicide bombers, one in a car packed with explosives, had carried out the attacks. "These attacks have reached today an unprecendented level, resulting in the killing of 11 Burundian soldiers, while 15 oothers have sustained serious injuries," the African Union said in a statement. A loud explosion shook the compound on Sunday morning. Witnesees said they had seen a car speeding towards the gate and then heard a blast and saw plumes of smoke rising into the air. The 3,500-strong African Union force also comprises troops from Uganda.