Stephanie Irene Aguilar, a respiratory therapist, was arrested Thursday on suspicion of attempted murder, corporal injury on a child and obstructing a peace officer.
Aguilar, 31, and her daughter were traveling in a GMC Yukon on Wednesday when she allegedly slammed the vehicle into the back of a tractor-trailer on the westbound 10 Freeway near Mills Avenue in Montclair.
Witnesses called 9-1-1 to report the crash, but then quickly relayed to dispatchers that the female motorist, later identified as Aguilar, had begun attacking the injured 8-year-old by punching the child and then slamming the girl's head into the SUV's center console, authorities said.
Passing motorists stopped and kept Aguilar away from the child until a California Highway Patrol officer arrived.
The woman, who was agitated, then attacked the CHP officer, injuring the officer's arms, Montclair police said.
The daughter reportedly suffered minor injuries. Aguilar was taken to Arrowhead Regional Medical Center in Colton as a precaution, authorities said.
She was released the following day and arrested, records indicate.
A motive for the attack has not been released.
Aguilar was booked into West Valley Detention Center in Rancho Cucamonga and was being held in lieu of $1 million bail.
She is scheduled to be arraigned Monday in West Valley Superior Court in Rancho Cucamonga.
Anyone with information on the case is asked to call the Montclair Police Department at 909-621-4771.