The "Daddy's Home 2" star was in a SUV that sideswiped and flipped after it was hit by another car, said Rafael Reynoso, spokesman for the California Highway Patrol, reported Variety
Ferrell, 50, was travelling to Los Angeles, along with three other persons, after attending an event in San Diego.
However, Mark Thompson, Ferrell's driver, and another passenger of the car, Carolina Barlow, are still hospitalised and receiving treatment.
"Will is staying close by as his friends are being treated, and has expressed his deep gratitude to the first responders who were immediately at the scene and to the hospital team that took such great care of them," UTA said.
"He's also grateful for all the well wishes he and his friends are receiving," it added.