According to the San Bernardino County Sheriff's Department, the chase began in Rancho Cucamonga when a deputy attempted to conduct a traffic stop on a driver suspected of DUI.
NOTE: The video above is from a previous report on this incident.
The driver wouldn't pull over and ended up smashing into the front of a white Ford Mustang in Upland. Four males were pronounced dead at the scene, according to authorities.
The three teens killed were identified as Jesus Guillen Jr. and Joel Jeremiah Silva - two 16-year-olds from Fontana - and Michael Adrian Gomez, a 17-year-old from Pomona.
The fourth person killed has not been identified.
It's unclear who was driving the vehicle.
A fifth victim inside the suspect's vehicle - a 13-year-old boy - survived the collision and was rushed to the hospital.
Two innocent victims were transported to a hospital but appeared to be OK, authorities said. Authorities told Eyewitness News a loaded firearm was found in the suspect's vehicle, a 2018 Hyundai, which had been reported stolen in Fontana.
The incident remains under investigation.