PHOENIX -- A hit-and-run driver sent a Phoenix grandmother and her granddaughter to the hospital Tuesday night.

Phoenix police said the driver plowed into the grandmother, who was riding a motorized scooter with her granddaughter in her lap. Officers said they were in the crosswalk at 30th Street and Thomas Road.

Witnesses said the impact tossed both the grandmother and the child into the air. The side mirror of the car was found in the middle of the street.

"The grandmother got hit. I could see the back of her head getting hit. The granddaughter was sitting on her lap, and the granddaughter ... hit her head," said Barbara McBride, a witness.

Shortly after the crash, investigators found the car in question -- a light-colored Toyota Camry -- missing one of its side mirrors. The car was found a couple of blocks from the crash. Witnesses said the driver, and possibly one passenger, were seen running from the car.

The grandmother was in surgery for broken bones Tuesday night, according to police. Officers said both were in serious condition.

Phoenix police said officers were out looking for the driver.