The collision occurred near Anaheim Street and President Avenue around 3:45 a.m.
Roberto Sanchez, 32, of Santa Ana and his partner Richard Medina were following a speeding white Camaro when both vehicles made U-turns. The patrol car was then struck on the driver's side by a Chevrolet Tahoe, which also had been heading eastbound on Anaheim Street.
The damage was so severe that firefighters had to extricate the officers from the wreckage.
Sanchez was later pronounced dead at Harbor-UCLA Medical Center. He had served for the Harbor Division for about six years.
His best friend and patrol partner remained hospitalized in critical but stable condition Sunday. Medina suffered serious injuries, including a broken jaw, but is expected to survive.
The occupants of the Chevrolet Tahoe immediately ran from the scene. Police detained two "persons of interest" about a mile from the scene. As of Sunday, no charges had been filed.
The search for the driver of the speeding Camaro also continued Sunday.
This is the third deadly accident involving the LAPD in recent weeks. Officer Nick Lee was killed on-duty when a truck slammed into his cruiser in Beverly Hills. A few weeks later, Officer Chris Cortijo was killed on-duty when he was rear-ended by an alleged drunk driver as he sat on his motorcycle at a stop light in Sun Valley.
Beck said LAPD Officer George Nagata also died Friday night of a heart condition. He was a 35-year veteran of the force.