The accident 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 Chevrolet Blazer traveling at a high rate of speed. The officer ended up pinned between two vehicles.
The LAPD Valley Traffic Division officer, a 26-year veteran of the department, was rushed to Providence Holy Cross Medical Center in Mission Hills. He underwent two surgeries and is now in a medically induced coma.
Family members and fellow officers have been visiting him at his bedside.
Capt. Maureen Ryan of the LAPD's Valley Traffic Division said the injured officer was her partner when the two were traffic cops in the division 25 years ago.
"He's dedicated to putting drunk drivers behind bars, and how tragic it is that he's now suffering at the hands of someone," Ryan said.
"He's a loving father, a husband, so we just ask that all of you keep him in your prayers," she added. "We've gotten an outpouring of support from the community and we're grateful."
The officer's name has not been released out of respect for the family's wishes.
Meantime, Qaneak Cobb, 33, was arrested for DUI and narcotics, according to LAPD Valley Traffic Division officials. Cobb was one of two people detained after Saturday's crash. Cobb is facing felony charges and is being held on $185,000 bail. As of Monday morning, she was still in custody.
The LAPD asked the public to donate blood on Monday to support the injured motorcycle officer. The event was organized to help the injured LAPD officer and to replenish the blood banks at the other six Providence Holy Cross hospitals across Southern California.
Fellow police officers, firefighters and members of the public turned out to show their support.
"I'm an L.A. city firefighter for 33 years and LAPD-LAFD, we're all in one, so I'm here helping a guy out in need," said Greg Pascolla of the Los Angeles Fire Department.
Another blood drive is planned for Tuesday at LAPD's Mission Area Station from 9 a.m. to 3 p.m. Officials urged people of all blood types to donate.
"No matter what blood type you are, they'll switch your blood type out for the officer's blood type," said LAPD officer Brett Robinson. "I know he's prepping for another surgery, they go through a lot of blood for those surgeries - blood is important just for the blood bank alone. To have it on hand, not just for the first responders, but for the general population as well is important - for you, me and everybody."