The son of a former politician has been charged with reckless driving causing death and drug use after he hit a group of students in Songkhla on Wednesday, killing two and injuring 13 others.

The suspect, Wissanu Tongsai, 35, told police that a motorcycle had suddenly cut in front of his pickup, causing him to lose control and his truck hit the students.

However, police said investigators did not believe him and conducted a drug test, which returned a positive result for amphetamines.

Ban Phru Tiao School had just carried out its annual scout hike that day. Many of the students were resting at a checkpoint, about 500 metres from the school.

The pickup truck, driven by Mr Wissanu, who is the son of a former member of the Samnak Kham Municipal Council, crashed into the checkpoint, where at least 20 people, both students and teachers, were carrying out safety checks.

The truck crashed into a road barrier at a high speed, sending the vehicle over the drainage ditch before smashing into the checkpoint.

Two students died at the scene.

The crash also injured 13 people, of which six were reported to be in critical condition.