(CNN) The man suspected to have shot and killed a police officer during a traffic stop in Newman, California, was in the country illegally, the Stanislaus County sheriff said Thursday.

The 33-year-old police officer, Ronil Singh, pulled over the suspect just before 1 a.m. Wednesday and a few moments later called out "shot fired" over the radio.

"Multiple agencies responded to assist, and Singh was found at the scene with gunshot wounds," the Stanislaus County Sheriff's Department, which is leading the investigation, said in a news release.

Singh was taken to a hospital, where he was pronounced dead, police said.

The sheriff's department has identified a suspect but is not releasing his name.

Read More