SANTA ANA, Calif (AP) — Eight firefighters were injured Thursday in a severe highway crash involving a fire truck in Southern California, authorities said.

Chief Brian Fennessy of the Orange County Fire Authority said the truck overturned on the California State Route 241 just north of Portola Hills.

The vehicle was transporting a ground crew after a 12-hour shift fighting a massive wildfire in Orange County called the Airport Fire. A ladder in the road caused the truck to swerve, strike a guard rail and overturn, Fennessy said.

At least one firefighter was flown by helicopter with others transported by ambulance to hospitals.

“All of our crews that were involved are going through a formal critical incident stress debriefing at our headquarters right now,” Fennessy said. “You can only imagine how traumatic it is for their brother and sister firefighter to see them injured like that on the freeway.”