THREE people were killed, including the suspect, in a shooting in the parking lot of an Oklahoma Walmart on Monday morning, U.S. police said.

At least nine shots were fired during the incident in Duncan, about 130 kilometers south of Oklahoma City, authorities said.

One man and one woman were found dead inside a car and a man, the suspect, was found dead outside of the car, said Duncan police.

It appears the shooter died from a self-inflicted gunshot wound, said Duncan Police Chief Danny Ford.

A semi-automatic handgun was found at the scene, police said.

A motive is not clear, Ford said at a news conference, but added it appeared the victims and suspect knew each other.

The suspect never was inside the Walmart, officials said, but the two victims, who died in the car, had been in the money center in Walmart before coming back to the car.

Walmart said no employees were injured in the shooting, which was described by the company as an isolated incident.

“As this is an active police investigation, we are currently referring additional questions to Law Enforcement and assisting however possible,” Walmart said in a statement.(SD-Agencies)