BAY POINT -- At least two people were hospitalized Tuesday morning when at least six cars were involved in a wreck on Highway 4 near Bay Point, the California Highway Patrol said.

Police were still investigating what caused the wreck, which involved a big rig and closed the two right lanes. The crash happened at approximately 6:05 a.m. in the westbound direction at the San Marco Boulevard onramp.

One person had to be cut free from the wreckage and was en route to John Muir Medical Center's trauma center, according to the CHP. It was not known immediately how many people were taken to a hospital, but the CHP said four ambulances were at the scene and that "multiple people" would be hospitalized.

The CHP closed the two right lanes at 6:38 a.m. and advised motorists to avoid the area if possible.

Check back for more details.