Two Las Vegas police officers and a civilian were gunned down Sunday morning when a married couple opened fire inside of a local pizza shop and Walmart.

According to officials, a male and a female suspect entered into CiCi's Pizza around 11:20 a.m. Sunday where they shot and killed Officer Alyn Beck, 41, and Officer Igor Soldo, 31, the New York Daily News reported.

One witness said she saw a white man wearing a tank top walk into the restaurant and pull out a gun. He then walked past her and shot and killed an officer who was sitting in front of her having lunch.

"I just sat down to have lunch. The officers were sitting in front of me, at the table right next to me -- and this man came in out of nowhere," Sheree Burns told CNN affiliate KTNV. "I thought he was going to get a drink, the way he walked up and walked past them. And then he turned around, pulled a gun on his right and shot the bald officer in front of me."

Other witnesses said that the second officer was then shot several times by the female shooter, but he returned fire. The officer later died at a hospital while in surgery.

The shooters reportedly covered the officers' bodies with a Gadsden Flag, which is a symbol of defiance dating back to the American Revolutionary War.

Moments later, Alvaro Lopez said that the shooters walked outside and confessed to shooting the cops as they crossed the parking lot toward Wal-Mart.

"They had a backpack, and I saw a gun in their hand," Lopez told CNN affiliate KLAS. "He just told me to tell the cops that it was a revolution, and that he'd just killed two cops inside CiCi's."

Assistant Sheriff Kevin MacMahill told reporters that the suspects took the officers' guns and ammunition and "made a statement -- something to the effect of, 'This is a revolution.'"

The suspects then entered into a Wal-Mart located about two blocks from CiCi's Pizza, at the intersection of Stewart and Nellis, where they killed a third victim at the entrance of the store. The civilian has not been identified.

Sheriff Doug Gillespie said that police are still looking of a motive.

"What precipitated this event, we do not know," he said. "My officers were simply having lunch."

According to CNN, a law enforcement official said that investigators found what appears to be a "manifesto" or some sort of writings at one of the scenes and that the couple held extremist views toward law enforcement.

In addition, investigators found flags or insignias with markings on them and two backpacks at the crime scene.