The crash was reported at about 12:20 p.m. Wednesday near Roxford Street, according to the Los Angeles Fire Department and the California Highway Patrol.
One of the drivers escaped his burning cab and passing motorists stopped to help put out flames on his clothes and body, according to the LAFD. The man was taken to a trauma center with critical burn injuries.
Some lanes were blocked while an investigation was conducted into the crash, causing a huge traffic backup. Only the truck lanes remained closed as of late Wednesday afternoon, according to a traffic log.
It took about 80 firefighters nearly 40 minutes to extinguish the flames from one of the big rigs.
No other injuries were reported.
City News Service contributed to this report.