The husband and wife duo suspected of killing two Las Vegas police officers and a civilian shopper at a Wal-Mart held some ideology "along the lines of militia and white supremacists," authorities told reporters Monday.

One of the shooters yelled, "This is a revolution!" Las Vegas police spokesman Larry Hadfield told The Associated Press.

Jerad Miller, 31, and his wife, Amanda, 22, have been named as the suspects. The couple had previously lived in Lafayette, Ind., and moved to Las Vegas in January, according to police.

The deadly rampage Sunday in the aging shopping centre northeast of the Las Vegas Strip took place in a matter of minutes. Police were called at 11:22 a.m. local time to CiCi’s Pizza, where one of the officers was able to fire back at his assailants. It's unclear whether he hit them, Sheriff Doug Gillespie said.

The attack at CiCi's Pizza killed officers Alyn Beck, 41, and Igor Soldo, 31, who are both husbands and fathers.

Although investigators are still trying to determine a motive, they said the shooters laid down a Gadsden "don't tread on me" flag — seen to symbolize American independence and freedom — as well as a swastika on Beck's body.

Wal-Mart shopper died 'heroically'

"We believe they equate government and law enforcement … as the oppressor," Las Vegas Assistant Sheriff Kevin McMahill said Monday during a press briefing. He said Jerad Miller was seen pinning a note to Soldo that stated "the revolution is beginning."

Las Vegas police officers are shown outside a Wal-Mart after a shooting incident involving local police. (Steve Marcus/Reuters,Las Vegas Sun)

Following the violence in the restaurant, shots were reported five minutes later at a nearby Wal-Mart, where a man was gunned down just inside the front door. The shooters exchanged gunfire with police before killing themselves, police said.

According to McMahill, Amanda Miller shot her husband before killing herself as part of an apparent suicide pact.

"No doubt the suspects have some apparent ideology that's along the lines of militia and white supremacists," McMahill told reporters, adding that investigators are looking into a possible link Jerad and Amanda Miller had with Cliven Bundy, whose Nevada ranch was the scene of an intense police standoff earlier this year over unpaid fees for grazing his cattle on public land.

The Wal-Mart victim was identified as Joseph Wilcox, 31, who McMahill said died "heroically" while trying to confront Jerad Miller.

Wilcox had been carrying a concealed weapon and likely believed he was dealing with a lone gunman.

'Showed no fear'

But Wilcox "did not realize Amanda Miller was with Jerad Miller and passed her directly," McMahill said, at which time she is said to have shot Wilcox in the ribs, killing him.

Gillespie thanked first responders and tactical units on Monday for taking swift action during the shooting to minimize the loss of innocent lives.

Photos of slain Las Vegas police officers Alyn Beck and Igor Soldo are displayed during a news conference Sunday afternoon. (Steve Marcus/Reuters, Las Vegas Sun)

"You showed no fear entering a building, knowing shots were being fired and that two of your brothers had already been shot," he said. "You used your training and good sense and developed a plan that forced the two suspects into a situation where their only avenue was to take their own lives."

McMahill said the Millers were armed with "numerous handguns" as well as a shotgun, and that a backpack in their possession contained "hundreds of rounds of ammunition," suggesting they were prepared for a lengthy gun battle.

At one point at this gun battle, Jerad Miller tried to shoot that door out of the back of the Wal-Mart, but … we prevented them from further endangering any other lives. — Kevin McMahill, Las Vegas assistant sheriff

He also stressed that quick-thinking tactical teams likely saved other people by barricading a patrol car against a back fire exit at the Wal-Mart to keep the suspects contained in the store.

"At one point at this gun battle, Jerad Miller tried to shoot that door out of the back of the Wal-Mart, but … we prevented them from further endangering any other lives," McMahill said.

Police also said that after completing hundreds of interviews, they believe the shooting to be an isolated act. The investigation involves more than 1,000 witnesses.

Nevertheless, for added safety, officers who normally work alone will be paired up with another officer for a time.

"When we are comfortable there are no additional threats that will occur ... [and] once we feel comfortable enough we'll be able to scale back, we will make adjustment accordingly," Assistant Sheriff Joe Lombardo told reporters.

Police say an armed couple ran into a Wal-Mart store after shooting two police officers at a nearby pizzeria and killed a man who confronted them before killing themselves in an apparent suicide pact. (John Locher/Associated Press)

The two slain officers were pronounced dead at University Medical Center. Beck had been with the department since 2001 and leaves behind a wife and three children. Soldo had been with the force since 2006 and is survived by a wife and baby, police said.

He was described as a good father and a "great guy" by his sister-in-law, Colleen Soldo of Beatrice, Neb. She said he attended high school in Lincoln, Neb., and previously worked as a corrections officer.

Jerad Miller was convicted of felony vehicle theft in Washington state and also had a criminal record in Indiana, police said.

The chain craft store Hobby Lobby issued a statement confirming that Amanda Miller had worked there.

The couple were married in August 2012, according to an Indiana marriage licence on file.

Sunday's killings came less than a year after the Las Vegas police department's most recent on-duty death. Officer David VanBuskirk died while rescuing a stranded hiker by helicopter on July 22, 2013.

The department has lost officers over the past decade in vehicle accidents and in an off-duty shooting, but the most recent on-duty shooting death happened Feb. 1, 2006, when Sgt. Henry Prendes was ambushed during a domestic violence call.