Suchat and Pol Lt-General Ronnasil Poosara, commander of the Southern Border Provinces Police Operation Centre, instructed police investigators to speedily investigate the incident and bring the culprits to justice.

Meanwhile, a source at an intelligence agency said the incident – which included the checkpoint attack as well as the use of road spikes and several pipe bombs, and the felling of trees and burning of tyres to obstruct officers’ pursuit – was probably carried out by a Runda Kumpulan Kecil (RKK) operations unit.

The attackers were probably led by insurgent suspects Abus Jeh-ali and Amad Leubaesa, who known to be active in Krong Pinang and Bannang Sata districts commanding at least 30 fighters, the source said.

The attack happened at 1.15am when the suspected insurgents opened fire at the checkpoint in front of the Krong Pinang Market in Tambon Krong Pinang, resulting in a 30-minute gunfight before the assailants retreated.

Pol Lance Corporal Thiraphat Sanitpoo, Pol Lance Corporal Ariaya Pimmatha, Pol Lance Corporal Jiranai Butda, Pol Lance Corporal Heramin Koseng, Pol Lance Corporal Prakit Chusup, Pol Lance Corporal Haimee Yakordung, Pol Lance Corporal Nikhom Thongkhao, Pol Corporal Prathom Thuaythong, Pol Lance Corporal Arthit Thanadnangseu, Pol Lance Corporal Worawuth Pongsri, Pol Lance Corporal Kanoksak Musikarak and Pol Lance Corporal Surasak Chaison were injured.

Yala police chief Pol Maj-General Krissada Kaewchandee led forensic officers and a bomb squad to inspect the scene afterwards. They collected five dud pipe bombs, fragments of three pipe bombs and 100 spent bullet casings from AK-47, M16 and HK assault rifles at the scene.

The bomb squad also removed another eight dud pipe bombs from a spot on Highway Number 41 (Yala-Krong Pinang).

An inspection of CCTV recordings showed that a team of as many as seven men opened fire at the checkpoint from the roofs of nearby houses while another armed group of eight men ran across the street to fire at the checkpoint. As more police officers came to reinforce the checkpoint, resulting in one attacker being injured, the assailants retreated into a nearby wooded area.

Two other teams of attackers reportedly placed the road spikes, felled trees and set tyres on fire on the highway.