At least 24 people were injured after an explosion at a hospital in Thailand’s capital, Bangkok, on Monday. Today is also the third anniversary of the military coup in 2014. The military junta’s chief, Chalermchai Sittisart, accused groups opposed to its rule of perpetrating the attack on Phramongkutklao Hospital, Reuters reported.

No group has claimed responsibility for the blast at the facility, which is used by serving and retired soldiers as well as their kin. “We found the pieces that were used to make the bomb,” Kamthorn Aucharoen, commander of the police’s explosive ordnance team, told Reuters. The official said closed circuit television camera footage was being monitored.

Deputy national police chief General Srivara Rangsibrahmanakul said the explosive was hidden in a container near the hospital pharmacy’s entrance. Officials are investigating if political rivals or Muslim separatists were responsible for the attack. “It does not have to be the junta anniversary. People who do not like the junta, given the chance, will do this,” Chalermchai said in a televised interview.

While an election is expected to be held by the end of 2018, the ruling military government has said it wants to increase its dominance over elected governments, the news agency reported. A new Constitution, approved by the King, allows it to do so.

Last week, around 61 people were injured in a car bomb blast in the border province of Pattani. Officials accused Muslim militants of staging the blast.