The crash occurred at the intersection of Saticoy Street and Lankershim Boulevard around 5:34 p.m.
Investigators say the officer was stopped a traffic light when he was struck from behind by a red SUV traveling at a high rate of speed. The officer was pinned in between two vehicles.
"There was debris all over the street," said Los Angeles police Sgt. Frank Preciado. "Now the reason why everything is marked is because it'll give an indication as far as the speed from the point of impact; it's a very strong impact, yes it is."
The LAPD Valley Traffic Division officer was rushed to Providence Holy Cross Medical Center in Mission Hills. A passenger inside the SUV was also hospitalized. His or her condition remains unknown.
"Chief Charlie Beck is at the hospital with the officers that are there, with the family members and he's visiting the injured officer in the emergency room," said Los Angeles police Cmdr. Andrew Smith. "The injured officer is in critical condition right now. Officers are in a nearby waiting room basically praying for his life."
Whether the officer's lights were flashing at the time of the accident remains unknown. The investigation is ongoing. No charges have been filed.
Investigators were interviewing all parties involved and nearby witnesses. The intersection was expected to be closed for several hours.