District of Columbia police say one man was killed and another was critically injured Friday night when they stood up while riding on the open-topped upper deck of a bus and their heads struck a highway overpass.

The victims, both believed to be in their 20s, were heading to a Washington Nationals baseball game.

The incident occurred around 8:45 p.m. The bus was westbound on the Southeast Freeway and passed beneath the 11th Street overpass.

Police have not identified the victims. Both were taken to local hospitals, where one died.

Shuttle buses typically carry Nationals fans to Nationals Park from RFK Stadium, but the Nationals Express shuttle buses typically are single-deck, closed-top models. It's not clear whether the people aboard the bus were members of a single group.