MOGADISHU - A car bomb that exploded outside a military base in the Somali capital on Sunday has killed at least 15 people, a military official said.The death toll could rise as a minibus carrying passengers was destroyed in the blast."At least 15 people mostly civilians died in the blast," Major Hussein Nur, a military official, told Reuters. "We do not know the exact figure of casualties. All the people on board the ruined minibus perished. Soldiers and other private security guards also died," he said.