Police Chief Jarrod Burguan said the two officers were involved in a "protracted gun battle" after they approached a group of six people at about 2 a.m.. An AK-47 and revolver were found at the scene.
The wounded officer, 31, was in "very, very, very critical condition" after being shot twice in the torso, Burguan said. The rookie officer, who graduated from the police academy two months ago, was not hurt.
Burguan said the two officers apparently found the group suspicious and decided to question them. Two young women and three men, all between the ages of 18 and 30, were held for questioning.
The group had been drinking at a nearby club, the chief said.
Some neighborhood residents reported hearing shots. One woman, who did not want to give her name, said the violence was unusual.
"I want to know why there were six people at 2 a.m. with heavy arms in this neighborhood," she said. "It's very unusual. I don't believe they live here. Nobody walks these streets with an AK-47."