Police in Thailand have said that an explosion at the King Mongkut Hospital in Central Bangkok on Monday (May 22) was caused by a bomb.

Twenty-four people were “slightly injured” following the explosion.

Of the 24 injured, three are still receiving treatment – mostly for injuries from broken glass, reports said.

Deputy Police Chief Sriwara Rangsiramanakul told reporters that the hospital is being searched.

“We found wiring and what seems to be the remains of battery parts that could have been part of the bomb. The intention of the attack is still unclear but this attack is unacceptable and I condemn this,” the deputy police chief said.

“We found the pieces that were used to make the bomb,” said Kamthorn Aucharoen, commander of the police’s explosive ordnance team.

“Right now, authorities are checking out closed circuit cameras,” he told Reuters.

Local broadcaster Thai PBS said the incident took place in a guest room for retired military officials. All of them were taken to the emergency room for treatment, it added.