At least six people have been killed in subway train collision in Washington, DC. The accident occurred on the outskirts of the city during the afternoon rush hour.

At least 70 people have been reported injured.

The city's first fatal Metro train crash in 17 years is being described as the "deadliest."

Adrian Fenty, Washington Mayor, said, "It is my preliminary understanding that this would then be the deadliest accident in the history of our Metro train transit system. We early on what to both express our condolences to all the family members."

A Metro system official says the first train was stopped on the tracks. It was waiting for another to clear the station ahead, when the trailing train plowed into it from behind.

Each of the six-car trains can hold as 12-hundred passengers.

Fire Chief Dennis Rubin says rescue workers treated 76 people at the scene and sent some of them to local hospitals. Six have critical injuries.

Dennis Rubin, Fire Chief Washington Fire Department, said, "A little bit after 5 o'clock we responded to what was believed to be a small incident. The first arriving company recognized the fact that apparently two trains had collided. A first alarm was sounded, followed by a second alarm. We're currently operating in a rescue mode at a third alarm response which is about 200 firefighters."

A search for more victims continued into the night.

The National Transportation Safety Board has taken charge of the investigation and sent a team to the site.