Three police officers and six civilians were injured, with four badly hurt, when a roadside bomb was detonated in Yi-Ngo district of this southern province on Thursday.
The incident occurred at about 9am on Ram Komut Road where police from the Yi-Ngo station were conducting a patrol by armoured vehicle.
The bomb exploded in front of a tea shop where some local residents were gathering. Three officers and six civilians were injured by the blast.
Four of the civilians were reportedly in serious condition as they were receiving treatment at Naradhiwas Rajanagarindra Hospital.
It was believed that insurgents detonated the device remotely when the police patrol arrived at the location.
Forensic and explosive ordnance disposal officials inspected the scene, and the investigation is continuing to track down the culprits.