A two-car traffic collision at 6:33 p.m. on Monday trapped one victim in a wrecked car at the intersection of North Altadena Drive and Villa Street.
Pasadena Fire Department spokesperson Lisa Derderian said it took firefighters almost 20 minutes to pull out the woman, who was seriously injured.
A total of four women were injured, and three were transported to a local hospital for treatment in serious condition.
Oner of the cars in the collision had contained three women, two of whom were elderly, authorities said.
There is no official word yet as the cause of the crash.