Bangkok: A bomb blast at a Bangkok army hospital injured at least two dozen people on the third anniversary of a military coup, police said.

It’s unclear who was behind the explosion on Monday at the Phramongkutklao army hospital, and what type of device was detonated, deputy police chief Srivara Rangsibrahmanakul said. There were no reports of fatalities, and police said investigators found the remains of wires, a circuit board and batteries at the scene.

Security was stepped up in the capital, army chief Chalermchai Sitthisart said at a briefing.

Thailand’s military rulers have sought to stifle dissent since seizing power from the democratically elected government of Yingluck Shinawatra. Thai King Maha Vajiralongkorn ratified a military-backed Constitution last month, paving the way for a return to some sort of democracy in 2018. Bloomberg