Three people died Sunday after an apparent ambush that started in a Las Vegas pizzeria.
The shooting carried over to a nearby Walmart.
Among the dead, two police officers and a pair of shooters.
A man and a woman shot the two cops as the officers were eating lunch at Cici's Pizza at about 2:20pm eastern.
Witnesses say one of the shooters yelled, "This is the start of a revolution" before firing at the patrolmen, who were identified as Officer Alyn Beck (42) and Officer Igor Soldo (32).
One of the cops was able to fire back at the duo before succumbing to his injuries, Sheriff Doug Gillespie said.
"My officers were simply having lunch when the shooting started," said Gillespie. "I can tell you that they were both family men, and they're leaving behind loved ones."
After the ambush, the suspects stripped the officers of their weapons and ammunition and went across the street to a Walmart, where they shot and killed another person, officials said.
Deputy Sheriff, Kevin McMahill, said one of the shooters, described as a tall white man, yelled "everyone get out" before unleashing a hail of bullets in the Walmart.
When cops arrived at the store, they found the one casualty at the front entrance, then exchanged fire with the suspects who fled further into the store, Gillespie said.
Officers then heard more shots.
The shooters had apparently killed themselves, in what officials described as "some kind of suicide pact."
Gillespie said the female suspect first shot the man and then herself.
The suspects haven't been identified, and the motive for the entire episode was unclear.
Officials stressed that the investigation was in its early stages.
In a statement, Walmart said the store was closed and they were working with local police.
"We express our deepest condolences to everyone who has been affected by this senseless act of violence," said spokeswoman Brooke Buchanan.
Cici's Pizza also put out a statement saying, "We are deeply saddened by this tragic event and out hearts go out to the families and friends of the officers."
They also said the store would stay closed until further notice.
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