The incident happened around 5:30 p.m. Sunday at the Pacific View Mall on the 3300 block of E. Main Street.
The injured person, whose identity has not been released, was taken to Ventura County Medical Center for treatment. The extent of the injuries was not known. Authorities said it is unknown if drugs or alcohol were involved.
The investigation is ongoing. Anyone with information was asked call the Ventura Police Department at (805) 339-4343.