The collision was reported around 12:50 p.m. on southbound Highway 101 near the Rengstorff Avenue exit, according to the CHP.
One car reportedly slammed into the back of another vehicle, sending it across multiple lanes of traffic, according to the CHP.
It was not immediately known how many people were injured nor the extent of the injuries.
The crash blocked two lanes for about 30 minutes, but all lanes were clear around 1:30 p.m., according to the CHP.
