Authorities have arrested a man suspected in the shooting and death of a police sergeant from the Hayward Police Department during a traffic stop Wednesday morning.

Hayward police identified the slain officer as Sgt. Scott Lunger, 48, of Brentwood, Calif., according to the Associated Press. The suspect, 21-year-old Mark Estrada, has been placed under arrest at a hospital where he is being treated for gunshot wounds, authorities said.

"We lost a warrior today," said Hayward Police Chief Diane Urban. "We've suffered a tremendous loss."

Sgt. Lunger was responding to an erratic driver around 3 a.m. with another officer when the shooting took place, authorities said, according to the New York Daily News.

"As Sgt. Lunger got out of the car and approached the driver's side of the vehicle, the driver shot Sgt. Lunger without warning," Chief Mark Koller said at an emotional press conference.

The second officer was able to return fire and call for backup before before Estrada sped off.

Estrada, from Oakland, who police say has gang ties, was arrested for Lunger's death. He is being treated at Highland Hospital in Oakland while under police guard.

Lunger was taken to Eden Medical Center in Castro Valley, Calif., where he later died, according to ABC's San Francisco affiliate ABC 7 News.

"He was an ideal police officer," Koller said. 

Police Lt. Eric Krimm said the Alameda County Sheriff's Department, Hayward Police and the California Highway Patrol are investigating the murder.