GRAY SUMMIT, Mo. — Investigators from the National Transportation Safety Board are in Missouri to look at the horrific interstate crash that killed a 15-year-old girl on a school bus and the driver of another vehicle.

NTSB Vice Chairman Christopher Hunt said today investigators will look into school bus safety and construction zone safety as they try to determine the cause of the wreck.

The accident happened Thursday on Interstate 44, about 40 miles from St. Louis. A semi cab slowed for road construction and was struck by a GMC pickup. Two buses carrying band students from a southeast Missouri town then slammed into that wreck.

The accident killed Jessica Brinker and the pickup driver, 19-year-old Daniel Schatz. Nearly 50 students were treated for mostly minor injuries.