The incident happened on the southbound lanes of the freeway at about 8:30 a.m. at the Malibu Canyon-Las Virgenes Road overpass.
California Highway Patrol officers said the woman, 27-year-old Gilani Taylor, was driving with her daughter, Jayla Taylor, when she lost control of her car, rear-ended a tanker truck, causing her Chrysler sedan to flip over and catch fire.
Several witnesses tried to rescue the woman, but were unable to remove her from the car due to the intense heat and fire. The woman was eventually able to extricate herself, but attempts to rescue her daughter were unsuccessful.
"This lady crawls out of the car, totally on fire from head to foot, so these guys already on the street ran over and pulled her over into like the fourth lane of the freeway," witness Dale Johnsen said.
Good Samaritans used their shirts to douse the flames on the woman.
The mother was airlifted to UCLA Medical Center, then to Los Angeles County-USC Medical Center, where she was treated for burns to 90 percent of her body, CHP officials said. She was listed in critical condition.
The driver of the truck was not injured. The trailer was hauling liquid nitrogen. CHP officials said it did not spill or leak.
Several southbound lanes were closed as fire and police crews arrived on scene. Traffic going both directions was snarled for miles.
City News Service contributed to this report.