The driver failed to yield, Gonzalez said. The officer later involved in the collision heard the police radio broadcast and drove southbound on Grand Avenue to assist, Gonzalez said.
Just before he reached McFadden Avenue, the officer drove into the northbound lane to get around traffic and collided with the tow truck, Gonzalez said.
Gonzalez described the accident as involving a partial broadside to the driver's side, not a head-on collision.
The officer was trapped in the vehicle and had to be extricated before taken to an area hospital as "a critical trauma patient," Gonzalez said.
The officer went into surgery this evening, Gonzalez said. No information as to his identity was released.
One of two male occupants in the tow truck "was taken as a trauma patient" to a hospital, Gonzalez said. He did not know the extent of his injuries. The other occupant refused medical treatment.
The California Highway Patrol was investigating the accident, Gonzalez said.
A witness said the tow truck driver had pulled over but the officer, who was going very fast, lost control while trying to get around another vehicle.
The tow truck driver "was not moving," said a bystander, Alberto Lemus. "He saw the police and pulled over."