CHP investigators say the crash happened just before 8:30 p.m. Sunday.
Initial reports indicated the car flew off the 210 Freeway. But the CHP later determined that the vehicle, a silver Honda, was actually driving on Michillinda Avenue, south of Foothill Boulevard.
Somehow the driver lost control and crashed into a raised concrete curb edge and then hit a chain-link fence, the CHP says. The Honda then collided into the freeway embankment and rolled over. It came to rest under the freeway overpass.
The driver and one passenger were declared dead at the scene. Another passenger was brought to a local hospital and then pronounced dead there.
The driver of the 2005 Honda has been identified as Andyn Bae, 17, of Temple City. He would have turned 18 on Monday.
The passenger who died at the scene was Eric Gullekson, 16, of Temple City. The passenger who died at the hospital was Nicholas Torres, 17, of Monterey Park.
Family members and friends expressed overwhelming grief for the victims at a candlelight vigil at the site of the crash Monday evening.
"He was loyal. He was there for me whenever I needed him. Always. He gave the best advice. He was the best at anything he tried to do," said Igy Watkins, Bae's friend.
Investigators don't know if alcohol or speed may have been a factor in the crash that took the lives of the three young men, each remembered for their love and life and dreams of a bright future.
"He was a good boy. He picked up skating, he was always with his friends. He was the one that made everyone laugh in the room," Luke Gullekson, Eric's brother.