Twelve people were involved in a head-on collision with three cars in Chula Vista.
The incident happened at Third and L Street just before 3 p.m.
Nine of those people refused treatment, and three were transported with moderate injuries.
An overturned Jeep Grand Cherokee, Honda minivan hit on the side and Nissan Titan with heavy front end damage were all involved in the crash.
The San Diego Fire Captain said he had no idea how the crash happened or which patients from which vehicles refused treatment. He had no comment on whether alcohol was involved in the crash.