LAS VEGAS (AP) -- A man and a woman ambushed two police officers eating lunch at a Las Vegas restaurant, fatally shooting them at point-blank range before fleeing to a nearby Wal-Mart where they killed a third person and then themselves in an apparent suicide pact, authorities said Sunday. The shooters walked into CiCi's Pizza and gunned down Officers Alyn Beck, 41, and Igor Soldo, 31, Las Vegas police officials said. One of the officers was able to fire back before he died, but it's unclear if he hit the suspects, Sheriff Doug Gillespie of the Las Vegas Metro Police Department said at a news conference Sunday afternoon. One of the shooters yelled, "This is a revolution," but a motive remains under investigation, Las Vegas police spokesman Larry Hadfield told The Associated Press. He added that "we don't know anything about the suspects yet." After shooting the officers, the suspects fled to the Wal-Mart across the street, where they killed a person inside the front door and exchanged gunfire with police before killing themselves, police said. The female suspect shot the male suspect before killing herself, Gillespie said. The victim's identity hasn't been confirmed, and the suspects' names haven't been released. "It's a tragic day," Gillespie said. "But we still have a community to police, and we still have a community to protect. We will be out there doing it with our heads held high, but with an emptiness in our hearts." Both 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. Pauline Pacheco was shopping at Wal-Mart when she saw the armed man and grabbed her father to escape, KLAS-TV reported (http://bit.ly/1pagYdj ). "We saw when the man was walking, he was shouting, yelling bad words, and suddenly he had a gun," she told the station. "It was terrible, it was terrible. That man was crazy." Assistant Sheriff Kevin McMahill said the male suspect yelled "everyone get out" before shooting at Wal-Mart. The suspects then walked to the back of the store. Gov. Brian Sandoval said in a statement he was devastated by the murders of the two officers and an innocent bystander in an "act of senseless violence." In a statement, Las Vegas Mayor Carolyn Goodman called the killings a "cruel act" and praised the officers for dedicating "their lives to protecting all of us in our community." Wal-Mart employees and shoppers were taken to a nearby clothing store to be interviewed by police. The restaurant and Wal-Mart remained closed as detectives processed evidence. McMahill said the investigation is "very complex" because it involves more than 1,000 witnesses. Wal-Mart expressed its condolences in a statement and that the company is working with police on the investigation. Cici's Pizza said in a statement the company was deeply saddened by the shooting and would keep the location closed until further notice. Sunday's killings come 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.