The Mississippi Highway Patrol was investigating a vehicle collision that killed three children and injured three others Saturday night on Interstate 55.

News outlets report that a 1-year-old girl, 6-year-old boy and 8-year-old girl sitting in the back seat of a car were killed in the Madison County crash.

The children were traveling in a Nissan Altima that was struck from behind by an 18-wheeler north of Canton, and the car crashed into a guardrail, said Mississippi Highway Patrol Master Sgt. Eric Henry.

A 6-month-old girl, along with two adults traveling in the front seat, survived the crash and were taken to the University of Mississippi Medical Center with injuries.

The driver of the semitrailer was not injured. The trailer of the truck was empty at the time of the crash.

Officials said the car may have been traveling less than the 70 mph speed limit because of low tire pressure.