BANGKOK — A bomb wounded 24 people at a military-owned hospital in Bangkok on Monday, the third anniversary of the army’s seizing power in Thailand.

The attack struck Phramongkutklao Hospital, leaving three people with shrapnel wounds to the face and neck, with most of the others suffering minor injuries, said Maj. Gen. Sansern Kaewkamnerd, a government spokesman.

The Thai military seized power in the kingdom on May 22, 2014, to derail a populist movement that had won several national elections over more than a decade. The coup was at least the 12th military takeover since Thailand abandoned the absolute monarchy in 1932.

Although the hospital that was bombed is owned by the military, it also treats civilians. Gen. Chalermchai Sittisart, the Thai Army’s chief of staff, said the blast took place “in a room full of people who were waiting for their medications.”