Police said at a news conference that surveillance video showed Rebecca Varela going into the store with Perkins. Meanwhile, police said, Wbiliado Varela was seen in a car parked in front of theirs in the Walmart parking lot. It was not immediately clear how long he had been in the vehicle.
After Rebecca Varela and Perkins got back to the vehicle, Duncan police Detective John Byers said, "Varela exits the vehicle, fires multiple rounds into the windshield and strikes Vescio and Perkins multiple times, and then goes to the rear of the car and turns the gun on himself, firing one time and killing himself.”
Authorities continued Tuesday to investigate a motive behind the attack, though Byers said it appeared to be the result of a domestic dispute.
"The relationship we have so far is that Mr. Varela and Ms. Vescio were married or at least common-law married," Byers said Tuesday. "We don’t know any relationship between Varela and Perkins at this time.
Byers said Rebecca Varela and Perkins were dating.
Authorities are reviewing video from multiple locations, including Walmart security video that depicts at least some of the shooting, Duncan Police Chief Dan Ford said.
Ford said there were several witnesses in the parking lot at the time of the shooting, some of whom ducked and ran for cover.
When officers arrived on the scene, Byers said they were initially distracted by an armed citizen who had drawn his own weapon after hearing gunshots.
“We did take his firearm at the time and later returned it to him after interviewing him,” Byers said.
Rebecca Varela worked at the Walmart but was not on duty at the time of the shooting, Byers said.
Update 3:40 p.m. EST Nov. 18: Police told The Duncan Banner that officers were called just before 10 a.m. local time to reports of the shooting at the Walmart in Duncan.
Police said they found two people, a man and a woman, dead in a car parked outside the store. A third person, a man, was found dead outside the car.
Authorities told KOKI-TV that the shooter, who was not immediately identified by police, shot and killed himself. No one else was injured.
On Monday, investigators were speaking to witnesses and working to obtain surveillance video from the store.
Update 12:45 p.m. EST Nov. 18: In a statement released to KOKI-TV, officials with Walmart said they were "assisting however possible" with the "active police investigation."
Walmart officials directed any questions about the case to law enforcement officials.
Update 12:40 p.m. EST Nov. 18: Duncan police said in a brief statement posted on Facebook that the weapon used in Monday's deadly shooting was a handgun. Officers have recovered the gun from the scene, authorities said.
Police said they found a woman and a man dead inside a car after responding Monday morning to reports of a shooting at the Duncan Walmart. Another man was found dead outside the car.
Officials continue to investigate.
Update 12:15 p.m. EST Nov. 18: Oklahoma Highway Patrol officials told KOKI-TV that the people killed Monday in a shooting outside the Walmart in Duncan included two men and a woman.
Authorities said the suspected shooter was among the three people killed.
Authorities continue to investigate.
Update 11:55 a.m. EST Nov. 18: Jason Hicks, district attorney for Caddo, Grady, Jefferson and Stephens counties, told The Duncan Banner that the scene was contained before 10:45 a.m. local time.
The newspaper reported that police were expected to hold a news conference on Monday morning to share more details on the incident.
Original report: Unidentified sources told KSWO the shooting happened outside the Walmart. Witnesses told the news station shots were also fired inside the store. Authorities did not immediately confirm the reports.
Check back for updates to this developing story.