The fire burned in dense bushes and trees next to the southbound lanes
The blaze was reported around 1:40 p.m. near the Woodside Road off-ramp.
The fire closed both on-ramps from Woodside Road to southbound Highway 101 as well as the southbound slow lane, according to the CHP.
The CHP says the southbound off-ramp to Woodside Road is now open. The Woodside Road on-ramp to southbound Hwy 101 is expected to reopen within an hour.
No injuries have been reported at this time.
It appeared the fire started near a homeless encampment next to the freeway.
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Bay City News contributed to this story.