Authorities say the vehicle struck a bump on J Street just after 9:30 a.m., and the officers, who were riding in the back of the open truck, fell out the rear.
The injured officers were sitting on a bench in the rear pickup portion of a truck operated by Seaside Park Emergency Management.
They were being driven back to their cars so they could go home and get some rest. For some reason the rear gate became loose and the bench fell out the back of the truck. The three officers toppled out with it.
Two of the officers were taken by helicopter to the hospital and a third was taken by ambulance.
They all sustained head injuries that were non-life threatening.
They are veteran officers and were directing traffic and security overnight at the fire scene. They were supposed to go home for rest and return at 4:00 Friday afternoon.