A blast has hit a bus carrying air force personnel down a main street in Yemen's capital, killing three, officials said.
Air force spokesman Colonel Mahdi al-Aidarous said 23 more were wounded, including five in critical condition with amputated arms or legs.
He said the bus was heading to air force headquarters when the blast went off. He said it most likely originated from inside the vehicle, but the official SABA news agency quoted later an air force statement as saying that an explosive device was stuck under the bus.
Private TV stations showed a damaged bus with blown-out windows and doors stained with blood, as security troops collected evidence that included two pieces of human flesh.
Yemen's government is battling militants linked to al Qaida, who regularly target the country's military.