WASHINGTON, June 23 (RIA Novosti) - The number of people killed in a two-train crash during the evening rush hour in northeast Washington has risen to 9 with 76 injured, CNN has reported.

Earlier reports said that at least six had died in the crash.

The general manager of the Washington Metro, John Catoe, said it remains unclear why the train which was pulling into a subway station had failed to stop and "for reasons we do not know plowed into the back of the train," which was awaiting instructions to start moving.

The accident took place between the Fort Totten and Takoma stations on the city's busiest Red Line soon after 5 p.m. local time (21:00 GMT) on Monday.

"The scene is as horrific as you can imagine," Washington Mayor Adrian Fenty told reporters at the scene.

President Barack Obama said he was "saddened by the terrible accident," and thanked rescuers for their efforts.

The Washington Metro said that of those wounded, 50 are slightly injured, while the fire department said six are in a critical condition.

The metro said on its website that the "Red Line service will be severely impacted on Tuesday, June 23," due to the accident.