Firefighters assisted the coroner's office in removing the bodies, which were "burned beyond recognition," from the wreckage for further investigation, Burbank Fire Capt. Peter Hendrickson said.
Lt. Larry Dietz of the Los Angeles County Medical Examiner-Coroner said fingerprints or dental records would be used to identify those killed depending on how badly they were burned.
There was one survivor, an 18-year-old woman who managed to crawl out of the burning Nissan and was found by police about 50 yards away from the wreckage when they arrived shortly after 4 a.m.
The woman suffered a broken leg and was being treated for non-life threatening injuries at the Los Angeles County Medical Center, Sergeant Darin Ryburn said. He said her father was with her at the hospital.
Paramedics reported smelling alcohol on her breath, Fire Battalion Chief Ron Barone said. Authorities don't yet know whether alcohol or drugs played a role in the crash - the woman was not the driver - but speed does appear to be a factor. The car burst into flames after striking a guardrail near an I-5 off-ramp and careened into a freeway pillar behind it.
The curving stretch of roadway has a posted 45 mph speed limit, but vehicles often fly off the freeway at speeds closer to 70 mph, and accidents have happened in the area in the past, according to authorities.
It's unclear if the surviving woman was wearing a seat belt. She was one of six total people squished into the car, which had only five seatbelts, Ryburn said.
Investigators will be conducting an interview with the woman, who they are not currently identifying, to learn more about the accident and how it occurred, Ryburn said.
The vehicle was fully engulfed in flames when firefighters arrived. "There was absolutely no possibility of any rescue whatsoever," Barone said.
The flames from the fire spread to nearby trees and brush and Barone said they were doused within moments of firefighters' arriving.
"It was a horrific tragedy for these five individuals that lost their lives, and we're working with the families," Ryburn said.