"They were ambushed," Clark County Sheriff Doug Gillespie said at a news conference this afternoon, though he said it was not yet known why the two were targeted.
"It's a tragic day, it's a very, very difficult day," Gillespie said. "We still have a community to protect. But we will do it with our heads held high. It is truly a tragic day."
The two cops were identified as Officer Alyn Beck, 42, and Officer Igor Soldo, 32.
The two shooters -- a man and a woman -- were later found dead, after they had shot another person at a Walmart store nearby, the sheriff said.
The two police officers were sitting in a CiCi's Pizza restaurant eating lunch late this morning when the man and woman walked in and opened fire on them.
"What precipitated this event we do not know," Gillespie said. "My officers were simply having lunch when the shooting started."
Both of the officers were hit, but one was able to return fire, he said.
The suspects then fled to the Walmart across the street, where they fatally shot a person inside and then killed themselves in an apparent suicide pact, the sheriff said.
The female suspect shot the male and then shot herself, Gillespie said.