At least 23 people were injured, mostly from broken window glass as a result of the explosion which was heard inside the Phramongkutklao Hospital in Bangkok's Rajthevi district, The Nation reported.

According to preliminary data, the incident took place at a reception room for retired military officials. All the injured were taken to the emergency room for treatment.

At first, it is reported that the cause of the explosion may be a gas leak or air condition compressor.