At least 24 people were injured following an explosion inside the Phramongkutklao Hospital in Bangkok's Rajthevi district on Monday morning, Thai media reported.
According to reports, the incident took place at a reception room for retired military officials. Local broadcaster Thai PBS said all of those injured were elderly. They were taken to the emergency room for treatment.
The hospital said in a statement that out of the 24 wounded people, three are still receiving treatment. The injuries came mostly from broken glass.
An army official who spoke with local media said the cause of the blast is under investigation.
**This story is developing**
