The collision occurred around 11:48 p.m. on northbound Lone Hill Avenue at the eastbound Interstate 210 freeway on ramp. One of the vehicles overturned, while the second vehicle received major front end damage.
Los Angeles County fire fighters treated three men, who all appeared in their late teens or early 20s, at the scene, while Glendora Police and the California Highway Patrol investigated.
At least two of the men in the overturned car were transported by ambulance, while the third remained at the scene.
Officers were not available for comment.