Making a left and right turn at nearly the same time. Who would be considered at fault? (California)

Scenario: There are two cars at a solid green light, one traveling east and making a left to go northbound and one traveling west and making a right to also go northbound. The car turning left turns into the innermost lane, the car turning right crosses 2 lanes and collides with left turner. Left turner has damage on right rear passenger door and right turner has damage on left front fender. Who would be considered at fault?

Edit: I'm not sure if it matters or not but collision did not occur at the intersection. Left turner was already established in the lane and traveling when right turner collided into them.