Two defence volunteers and two civilians were injured in a motorcycle sidecar-mounted bomb explosion in front of Tha Phraya Sai Dam in Muang district of the southernmost province of Narathiwat last night.

The four victims were injured by the force of the explosion and shrapnel. They were rushed to the provincial hospital.

Following the explosion, police cordoned off a wide area around the scene of the blast, as a bomb disposal squad searched the area for other devices. None were found.

Witnesses told police investigators that the motorcycle and sidecar, rigged with an explosive device, was parked in front of the dam Monday evening and the rider left the scene. The device detonated at 9.35pm.