The crash happened shortly after 4 a.m. Sunday on northbound I-280 near Page Mill Road.
Thomas was driving north on I-280 in a 1999 BMW with three passengers when the car somehow collided with a 2012 Nissan and struck a tree, according to the California Highway Patrol.
The BMW was cut in half, and Thomas was ejected even though he was wearing a seat belt, CHP officials said. He was pronounced dead at the scene.
The Nissan overturned and landed with part of its roof on top of the concrete center median wall but the driver was able to get himself of the car, according the CHP.
He and the three passengers in the BMW were taken to Stanford Hospital.
The Nissan's driver, Johnson Chao, 46, of Redwood City, and BMW passengers Matthew Navarra, 21, of San Carlos, and Ashley Farr, 21, of Sacramento, all suffered minor injuries, CHP investigators said.
The third passenger in the BMW, Megan Smith, 19, of San Francisco, had moderate injuries, according to the CHP.
The crash remains under investigation.