A 5-year-old boy and his grandmother were critically injured when their SUV collided with a mail truck Friday night in Magna.

The family was in a Chevrolet Tahoe traveling west on State Road 201 when it turned south at 8000 West in front of a large truck contracted to carry mail for the U.S. Postal Service, troopers said.

The grandmother and grandson remained hospitalized Saturday, troopers said. An infant granddaughter and the grandfather were treated and released.

The driver of the mail truck was not injured.

It is not clear who was driving the Tahoe, troopers said. The occupants of the Tahoe say the man was driving, but responders and the mail truck driver said the injured woman was driving.