SANAA, Yemen (AP) - A powerful blast ripped through a bus carrying air force personnel down a main street in Yemen's capital on Sunday, causing at least a score of casualties, officials said. Air force spokesman Col. Mahdi al-Aidarous said about 24 officers and soldiers were on the bus, and at least 20 were either wounded or killed. The bus was heading to air force headquarters when the blast went off, most likely originating from inside the vehicle, he said. The bus appeared to be torn open by the explosion, its roof ripped apart and its sides blown out. Seats and debris were scattered on the pavement, next to bodies and blood. Yemen's government is battling militants linked to al-Qaida, who regularly target the country's military.