A metal bar fell of a big rig and crashed through the car driving behind it, impaling the passenger's leg, California Highway Patrol officials said of the "unusual incident" that took place Saturday morning in the Sacramento area.

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CHP said the metal bar fell off the big rig, struck the roadway, and then bounced up and entered a Chevrolet Impala through the engine compartment before penetrating the passenger compartment and impaling the female passenger's leg.

The Impala's driver exited the freeway and called 911. The female passenger received medical aid at the scene from first responders and was transported to the hospital, where she was reported to be in stable condition, CHP said in a news release posted on Facebook.

The driver of the big rig did not stop, CHP officials said. CHP is asking the public for assistance in locating the big rig and its driver.