The boy was walking on the sidewalk of Wolfe Road at about 12:30 p.m. when he allegedly climbed onto the tow bar as the tractor-trailer was stopped at a red light, waiting to take the on-ramp to southbound Interstate Highway 280, the CHP reported.
When the light turned green, the truck accelerated and the victim either jumped or fell from the tow bar. He was struck and killed by the tires of the rear trailer, according to the CHP.
The tractor-trailer continued onto Highway 280 and it is unknown whether its driver had known the boy had climbed onto tow bar.
Witnesses were not able to describe the tractor but said the dual gravel trailers were white.
The CHP initially had reported a woman was killed after being ejected in the collision, but since said the teenage boy was the victim.
Anyone with information regarding the collision is asked to call the CHP at (408) 467-5354 ext. 271 or (707) 551-4100.
The Wolfe Road on-ramp to southbound Highway 280 was shut down until about 3:20 p.m. while authorities investigated the crash.