The gunman who killed two people outside an Oklahoma Walmart had been married to the woman he killed, and the other victim was thought to have been dating her, police said Tuesday. The shooter then killed himself Monday morning in Duncan.

“It appears right now to be a domestic dispute,” Duncan police Det. John Byers said, although he said investigators are looking into a motive.

The gunman was identified Tuesday as Wbiliado R. Varela Jr., 43, of Duncan. The victims were identified as Rebecca N. Vescio-Varela, 31, also of Duncan; and Aubrey P. Perkins, 39, from Minco, which is around 60 miles north of Duncan.

Investigators believe that Varela had been either married to or had a common-law marriage with Vescio-Varela, and that Vescio-Varela and Perkins were in a dating relationship, Byers said at a news conference.

He said that Varela fired into the windshield of the car that Vescio-Varela and Perkins were in and may have also opened the driver’s side door and fired more rounds.

Varela then went to the rear of the car and shot himself in the head, police said.

Police said in a statement Tuesday morning that the shooting is still under investigation.

Byers told reporters that investigators found 13 shell casings and live rounds at the scene of the shooting. Police said a semi-automatic handgun was found by Varela's body.

Another man who was armed approached the scene after the shooting, but police believe there was no interaction between him and the gunman, and that he approached after Varela killed himself. He was interviewed and his firearm was returned to him, Byers said.

Vescio-Varela is believed to have been an employee at the Walmart, Byers said.

Duncan is a city of around 23,500 around 70 miles southwest of Oklahoma City.