The single-vehicle crash happened around 1:45 p.m. near the 101 Freeway interchange.
The California Highway Patrol said the 72-year-old male driver lost control of a black Mercedes Benz station wagon, veered across the lanes and hit the center divider. The vehicle then burst into flames.
Officer Don Thompson, a member of the LAPD Bomb Squad, was traveling on the southbound 405 Freeway when he saw the crash. He stopped, jumped over the concrete jersey wall and pulled the driver out of the burning car. Authorities said two civilians also stopped to help.
The driver was taken to the hospital to be treated for moderate injuries. Thompson sustained first- and second-degree burns to his hands and leg, along with smoke inhalation and abrasions.
The flames were quickly extinguished, but some lanes on the freeway had to be closed for a couple of hours.
The cause of the crash remains under investigation.