+ A
A -
Authorities initially pointed to a gas leak or an explosion of an air conditioning compressor as possible causes, local media reported.
But, following an investigation, police confirmed the explosion was a bomb, citing remnants of a bomb circuit, electrical wiring and batteries found during a search at the hospital.
The pipe bomb blast had a 2- to 3-metre radius. The explosive was hidden in a flower vase, in a public area of the hospital, Deputy National Police Chief Srivara Ransibrahmanakul said.
No suspect had been identified and investigations would continue, Srivara added.
The explosion occurred as Thailand marked the three-year anniversary of the May 22, 2014, coup. Thailand remains under military rule, with the junta promising general elections in late 2018.
Monday's explosion came one week after a pipe bomb exploded in front of Thailand's national theatre, slightly injuring two women.
The explosion also happened in close proximity to the Grand Palace where the late king Bhumibol Adulyadej is lying in state.
Last month, a pipe bomb exploded in front of an old government lottery office, wounding two cleaners.
