Acting on a tip-off, police set up road checkpoints on Mae Chan-Chiang Saeng Rd in Mae Chan district. The checkpoint was approached by a pick-up truck and three cars at about 9pm.
The vehicles ran the checkpoint, and when police gave chase, they noticed that the three cars tried to keep them from getting near the pick-up, said Pol Colonel Noppadon Nilmanon who headed the operation.
Two men in one of the cars opened fire on the police, prompting them to return fire. Officers shot the tyres of the pick-up truck, prompting both the car and the truck to stop. The other two cars managed to flee the scene.
Police said the driver of the truck lobbed a grenade at the police and tried to get away, but police shot and injured him. He was identified as Prateep Saeyang, 20. He later died at a hospital.
The two other suspects were identified as Sitthichai Saeyang, 35, and Salidet Saethao, 30.
Chalerm held a press conference at the Royal Thai Police Club yesterday to announce the arrests.
The seized drugs were worth about Bt600 million, he said.