The crash happened about 8:10 p.m. on Colorado Street Bridge near San Rafael Avenue, according to CHP Officer Patrick Kimball.
A CHP unit began chasing the Toyota Corolla after a motorist reported at 7:52 p.m. that it was swerving in lanes, Kimball said.
The Toyota was located at 8:09 p.m. and crashed one minute later into a Nissan Maxima, Kimball said.
Firefighters responded to the scene and reported they were treating four people, including one trauma patient and two people who complained of pain.
One of the patients was a child, according to the Pasadena Fire Department. Three of the patients were trapped in the wreckage and needed to be freed, the fire department reported.
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