Witnesses said the massive truck rollled two times, and crushed a GMC Yukon, which landed upside down, trapping the man driving.
It took more than a half hour to free him from his SUV, and he was airlifted to John Muir Hospital in Walnut Creek, where he was reported in serious but stable condition. Witnesses said he was talking and moving, when he was extricated from his vehicle.
Vallejo Fire Department spokesman William Tweedy said the crash occurred Saturday as firefighters were responding to a kitchen fire.
He said the ladder truck had its sirens on when it collided with a car at a street intersection, causing it strike two vehicles, overturn twice and strike a third vehicle.
The truck came to a stop a block away from the initial collision.
Nichelini said that the ladder truck, when rolling, took out various street signs along Sonoma Boulevard finally coming to a rest in the intersection of Pennsylvania Street and Sonoma Boulevard after striking a fire hydrant and crushing another vehicle.
The crushed vehicle was flipped on its back and the driver in the crushed vehicle required extraction. The driver was extracted after about 40 minutes.