At least 37 people were killed and 66 others wounded today in the Yemeni capital city of Sanaa, when a suicide bomber rammed a minibus packed full of explosives into a line of recruits at the nation’s police academy.

At least three of the slain were civilian bystanders, while the overwhelming majority were would-be recruits for the police force. No group has yet claimed responsibility.

It is believed, however, that the attack is the work of al-Qaeda in the Arabian Peninsula (AQAP), which has launched similar strikes in the past. Police are operating under the assumption of AQAP having done it.

AQAP is believed to have enjoyed a surge in recruitment in recent weeks, owing to the increased influence of Shi’ite Houthi rebels. Sunni tribesmen have been backing AQAP as a sort of counterbalance.