The incident happened around 1:10 p.m. in the area of Alemany Boulevard and the southbound on-ramp. The tanker was carrying gallons of cooking oil, but there are no immediate health hazards at this time, officials said.
Video from the scene can be viewed in the media player above.
The truck rolled over and landed on its side, according to California Highway Patrol. Fire crews were called to the scene, but no fire was reported.
The tanker had 60 gallons of cooking oil, which weighed approximately 80,000 pounds, CHP said.
As of 1:30 p.m., the on-ramp on Alemany towards southbound 101 is closed, authorities said. It is unknown at this time when that road will reopen.
This story will be updated as KRON4 learns more.