A tour bus traveling southbound on the Baltimore-Washington Parkway overturned early Sunday.

U.S. Park Police responded to a report of the crash around 12:45 a.m. south of where the Parkway, also known as MD 295, intersects with MD 198 near Fort Meade.

The bus was carrying approximately 40 passengers, one of whom was transported to a hospital with life-threatening injuries, according to police.

An investigation is ongoing.