An inquiry is underway after a deputy sheriff fatally shot an off-duty police officer after mistaking him for an armed robbery suspect.

The Clark County Sheriff’s Office deputy was one of several officers responding to an armed robbery underway on Saturday, 29th January.

The robbery took place at a Chevron convenience store in the census-designated place of Orchards in Clark County in the north-western US state of Washington.

According to reports, the suspect pulled a gun on the worker on duty and demanded cash.

According to the authorities, the unnamed suspect then fled the crime scene in a stolen Mercedes, which he drove towards the city of Battle Ground.

He then abandoned the car after the police immobilised it with spike strips.

He fled on foot towards a residential property, which he tried to gain entry to, claiming he had been involved a road accident and needed help.

The home belonged to Vancouver Police officer Donald Sahota, 52, who stepped outside with his work gun, only for the man to turn violent.

Before Sahota had the chance to use his gun for self-defence, the man reportedly stabbed him several times before entering his property.

The Clark County Sheriff’s Office deputies arrived on the scene to see Sahota attempting to recover his gun and run back into his residence.

Apparently mistaking him for the suspect they were in hot pursuit of, one of the deputies opened fire, hitting him and causing him to slump on his porch.

Despite receiving first aid, Sahota passed away at the scene, leaving behind a wife and two children, ages not reported. The true suspect then willingly gave himself up.

In a press release, Vancouver Police Chief James McElvain said: “My heart goes out to Officer Sahota’s family and friends and those of us in his VPD family as well. His death is a tragic loss, and he will be deeply missed by many.”

The Vancouver Police Department reported that the Lower Columbia Major Crimes Team is investigating the incident.