The crash happened at the northbound connector to the 215 Freeway at approximately 2 a.m.
Three males and one female, all reportedly young adults, were killed in the accident.
CHP Officer Andrew Murphy said the BMW slammed into a pole, possibly because it was going too fast to maneuver through the transition road.
The crash shut down the connector ramp for several hours, but it has since reopened.
The victims' names have not been released.