Last Updated Jun 8, 2014 10:45 PM EDT
LAS VEGAS - A man and a woman ambushed two police officers in a pizza parlor Sunday, killing them both, then ran to nearby Walmart where they shot dead a third victim before taking their own lives, police said.
Police said no other suspects were being sought.
"I am sad to report that two of my officers were killed in the line of duty and an an inocent civilian also lost their life," Sheriff Doug Gillespie told reporters. "Two suspects responsible for this also lost their lives."
The violence erupted about 11:30 a.m. at a Cici's restaurant on Nellis Boulevard. Two officers from the Las Vegas Metropolitan Police Department were eating lunch when a man and woman "came in and immediately engaged the officers with gunfire," said Officer Laura Meltzer, a spokeswoman for the department.
Witnesses in the restaurant said they heard one of the suspects yell, "This is a revolution."
After shooting the officers, the suspects ran to a Walmart across the plaza from the restaurant. They shot and killed a woman near the entrance to the store, than ran inside the Walmart. Police entered the front and back of the store and exchanged gunfire with the suspects. The female suspect shot the male suspect and then killed herself, Gillespie said.
"I say to the community and I say to my officers, it's a tragic day," the sheriff told reporters.
Nevada Gov. Brian Sandoval called it an "act of senseless violence."
Gillespie said investigators had no motive for the attacks.
"What precipitated this event, we do not know. My officers were simply having lunch when the shooting started," the sheriff said.
Gillespie said one of the officers managed to fire back at the suspects, but it was not immediately clear whether he hit either of them.
He identified the slain officers as Alyn Beck, 41, and Igor Soldo, 31.
"Both are family men, leaving behind loved ones," the sheriff said.
Beck, a member of the force since 2001, had a wife and six children. Soldo, who joined the department in 2006, leaves behind a wife and a baby.
Gillespie said the woman killed inside the Walmart had not been identified yet and he did not release any further information about that victim.
He did not release any information about the suspects.
Pauline Pacheco, who was shopping at in Wal-Mart, told CBS affiliate KLAS she saw the male suspect and grabbed her father so they could escape.
"We saw when the man was walking, he was shouting, yelling bad words, and suddenly he had a gun," she said. "It was terrible, it was terrible. That man was crazy."
The Wal-Mart Corp. expressed shock at the incident.
"We express our deepest condolences to everyone who have been affected by this senseless act of violence," the company said in a statement. "Our store is currently closed. This is still an active investigation and we are working with local police."