The crash happened about 1:10 a.m. Sunday on Foothill Boulevard near Lime Avenue in Fontana.
The victims, all from Fontana, were identified as Javier Contreras, 18, Rebecca Garcia, 16, Pedro Rivera, 18, and Raquel Garcia, 18.
Authorities said the driver, Contreras, was speeding on Foothill Boulevard when he lost control and crashed, causing the car to go up in flames.
Contreras and Rebecca Garcia died at the scene. Rivera and Raquel Garcia were transported to the hospital, where they later died.
Fontana police are investigating the crash.