(KRON) — Three westbound lanes were blocked off after a severe collision on the Bay Bridge Saturday afternoon, the California Highway Patrol confirmed to KRON4.

It is unknown how many people suffered injuries in the crash that began just after 12:30 p.m. At least two lanes on the westbound lanes Bay Bridge heading towards Treasure Island are still closed at this time, CHP says.

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CHP is still waiting for tow trucks to arrive on scene and remove the affected vehicles. Traffic is still impacted at this time, CHP tells KRON4. Law enforcement says four vehicles may have been involved in the crash.