According to a release from the police department, the suspects made their way to the rear of the store and exchanged gunfire with officers who had converged on the store, entering from the front and the rear.
"Minutes later, a second volley of gunshots was heard, and it is believed the female suspect shot the male suspect before turning the gun on herself," said the release.
The officers were both pronounced deceased at the UMC Trauma Center. The department identified the officers as Alyn Beck, 41, and Igor Soldo, 31. The victim's identity hasn't been confirmed, and the suspects' names haven't been released.
Walmart employees and shoppers were taken to a nearby clothing store to be interviewed by police. The restaurant and Walmart remained closed as detectives processed evidence. McMahill said the investigation is "very complex" because it involves more than 1,000 witnesses.
Al Jazeera and wire services