The two-vehicle crash occurred at 2:07 a.m. at Etiwanda and Fourth Street in Ontario, just outside of the Auto Club Speedway.
Officer Bryce Hanes had just dropped off an arrestee at West Valley Detention Center in Rancho Cucamonga when he was broadsided by a 2008 Dodge Charger, San Bernardino Police Chief Jarrod Burguan said.
Burguan said Hanes had the right of way and the alleged DUI driver ran a red light while heading east. The collision sent Hanes' squad car across the intersection.
"We do have an eyewitness to the collision that indicated that the officer did have a green light at the time of the collision and that the other driver did run a red light," Ontario police Det. Bill Russell said.
Hanes suffered massive injuries and was rushed to Kaiser Permanente Fontana Medical Center, where he was pronounced dead.
The alleged DUI driver was also transported to a local hospital with minor injuries. He has since been released from the hospital and is currently being interviewed at the Ontario Police Department.
The suspect's name has not been released but Ontario police have identified him as a 27-year-old Fontana resident.
He was arrested on suspicion of vehicular manslaughter and felony DUI causing injury or death, Ontario police Sgt. Jeff Higbee said.
Hanes, of Redlands, leaves behind a wife and three children under the age of 12.
Several streets around the crash site were expected to be closed for several hours as Ontario police work to determine the rate of speed at which both vehicles were traveling and whether Hanes was wearing a seatbelt.
Meanwhile, fellow officers in motorcycles, patrol cars and off-duty vehicles paid their respects to Hanes during an emotional procession on Thursday from Kaiser Permanente Fontana Medical Center to the San Bernardino County Coroner's Office.
"Bryce was one of those guys that come to work every day with a great attitude. He got along well with all of his coworkers. He really loved his job, and he loved what he did," Burguan said.
A memorial fund has been set up by the San Bernardino Police Officers Association to assist the Hanes family. For more information, visit http://thesbpoa.org/sbpo-foundation/bryce-hanes-memorial-fund.