Police investigate the scene of an accident at Seventh Street NW and Pennsylvania Avenue in which two pedestrians were struck by a bus at about 9:30 p.m. Wednesday. (Clarence Williams/The Washington Post)

(Update: Two pedestrians die after being struck by tour bus in downtown Washington)

Two pedestrians were hit by a tour bus and critically injured Wednesday night along Pennsylvania Avenue in Northwest Washington, D.C. officials said.

Few details were available late Wednesday, but authorities responded to the scene at 9:40 p.m. at Seventh Street NW and Pennsylvania Avenue, police and fire officials said.

Medics took the two patients to the hospital with life-threatening injuries after they were hit by the tour bus, a fire department spokesman said.

The D.C. police major crash unit was investigating the cause of the crash. No further details were immediately available. The tour bus, which had the company name Eyre Bus, Tour, Travel on the side, was parked in the 700 block of Pennsylvania Avenue near the Navy Memorial and across the street from the National Archives.

No further information was immediately released.