UPDATED | June 5, 2017 11:58 AM

ARLINGTON (CBSDFW.COM) – A 9-month-old baby was killed and his mother seriously injured in an early morning crash that temporarily closed State Highway 360 in Arlington.

The accident involving a sedan, with the mother and child inside, and a man in a pickup happened just after 5:15 a.m. near Pioneer Parkway. Arlington police Sgt. VaNessa Harrison said, “We had a vehicle stalled in the southbound lanes of traffic and it was struck by a pickup truck.”

The southbound side of the highway was closed and traffic forced off at Park Row.

The baby boy was in a safety seat when the truck crashed into the stalled Honda Accord. The child’s mother was throw from the car, while the baby remained strapped in the back seat. Both the child and his mother were rushed to a local hospital, but the child died from his injuries. The baby’s mother, who has not been identified, remains hospitalized in serious condition.

The male driver of the truck was not seriously hurt. Police say that man is cooperating with the investigation. “The officers on the scene are still trying to investigate what exactly caused the accident… we don’t know if it was driver inattention or what could have possibly caused it,” explained Harrison.