SAN DIEGO — An unlicensed teen driver was arrested Saturday on suspicion of DUI after the vehicle he was driving crashed off a freeway in Mission Valley, killing two of the people inside.

Speed, alcohol and drugs were all possible factors in the crash, the California Highway Patrol said.

A 2008 BMW was traveling west along Interstate 8 at about 3:15 a.m. when it attempted to take the state Route 163 transition ramp at a high speed. Police said the vehicle veered over the ramp’s concrete wall and fell about 40 feet down an embankment, where it crashed into a tree and caught fire.

Five teens between the ages of 15 and 19 were in the car at the time of the crash, the CHP said.

The driver and two other teens were able to escape the burning vehicle. Two boys, both 15, were trapped in the back seat, Salvador Castro with the CHP said. Their bodies were found after firefighters put out the flames.

The three surviving teens were taken to two nearby hospitals with major injuries.

Authorities said the 17-year-old driver did not have a license and was arrested on suspicion of DUI and vehicular homicide.

“People drive way too fast for the conditions,” Castro said. “It was pretty slick with the rains that occurred yesterday. It does leave the roadway slick; all the oil comes up.”

The southbound lanes of SR-163 from Friars Road to the westbound I-8 off-ramp were closed for hours after the crash.

All lanes were reopened at about 3 p.m.

The identities of the victims were not immediately released.