An explosion at the Army Ordnance Department near Saphan Daeng Bridge in Bang Sue district of Bangkok about 10am on Monday injured five personnel.
Army spokesman Winthai Suvari said the explosion happened while technicians were disassembling an RPG launcher in which a grenade remained stuck inside .
They were in a maintenance tunnel for safety reasons.
The five technicians suffered head wounds and chest injuries and were rushed to Phramongkutklao Hospital, where they were reported to be out of danger, the spokesman said.
"This accident happened inside a military unit and there was no impact outside it," Col Winthai said.
The injured were identified as Banjerd Chiangsai, Bancha Sriprayoon, Kantapol Pakcharoen, Santiparp Kerdnoi and Teerapat Sriniyom.
Lt Gen Tharee Wuthipanich, director-general of the Army Ordnance Department, said later there was no grenade inside the launcher, but the propellant had exploded during a regular repair.
Injured ordnance technicians are rushed to Phramongkutklao Hospital in Bangkok on Monday after propellant left in an RPG launcher exploded as they tried to repair it. (FM. 91 Trafficpro photo)