BANGKOK, Thailand - A Thai police officer fatally shot a Canadian man and wounded his pregnant companion during a scuffle outside a bar in northern Thailand, authorities said Monday.

The officer told investigators the shooting was an accident but he was charged with premeditated murder, said police Col. Sombat Panya of Pai district in northern Mae Hong Son.

John Leo Del Pinto, 25, died early Sunday of two gunshot wounds -- one to the face and one to the torso -- and his partner, Carly Reisig, also of Canada, was in hospital with a bullet wound in her body, Sombat said.

Their hometowns were not immediately known, Sombat said.

The couple, who had rented a home in the town Mae Hong Son, were drinking at a bar in Pai and began arguing, Sombat said, citing witnesses.

Outside the bar, their argument turned physical and when a police officer tried to intervene the couple attacked him, Sombat said.

The officer, Sgt. Uthai Dechawiwat, told investigators Del Pinto tried to grab his pistol and the gun "accidentally went off'' three times, Sombat said.

However, Uthai was charged with premeditated murder for Del Pinto's death and with "intent to kill'' in connection with Reisig, Sombat said. Uthai was released on bail.

The couple had rented a home in Mae Hong Son, on the border with Myanmar, for several years but took regular trips in and out of Thailand to extend shot-term tourist visas, Sombat said.