Seven people were injured in a bomb attack in Yala's Muang district yesterday morning, most of them territorial defence volunteers.
Police said the explosion took place in front of a house in an area where a team of defence volunteers was on duty. One of the volunteers, Sakchai Boonsas, sustained serious injuries.
Sakchai was about to sit on a chair in front of the house when a bomb hidden under the chair went off, detonated by a cellular phone.
The blast left a crater in the ground about 10 centimetres deep and 30cm wide.
Police believe insurgents carried out the attack to fan unrest in the deep South, which has seen bloody attacks going on almost on a daily basis for about a decade.
After the explosion, Yala Police chief Pol Maj-General Songkiat Watakul ordered that recordings from nearby security cameras be examined to identify the attackers.