June 22 (Bloomberg) -- At least six people were killed and scores injured when a Metro train crashed into the back of another on the Washington transit system today in the worst accident in its 33-year history.

Rescue dogs were going through the wreckage and more bodies could be found, said Alan Etter, a Washington fire department spokesman. Of 76 people taken to hospitals, six were in critical condition, Fire Chief Dennis Rubin said.

The rush-hour crash occurred on the system’s Red Line in Northeast Washington. One train plowed into another that was stopped waiting for an order to go on, Metro General Manager John Catoe said at a news conference. One car, its front sheared off, landed on top of another.

“The scene is as horrific as you can imagine,” Washington Mayor Adrian Fenty said at the scene.

The woman operating the train that failed to stop was one of those killed, according to the Washington Metropolitan Area Transit Authority, which operates the Metro system.

The collision and derailment occurred at about 5 p.m. local time between the Takoma and Fort Totten stations, Metro said in a statement. Washington’s Metro is the second-largest U.S. heavy-rail transit system after New York City’s subway, according to the American Public Transportation Association. The collision was above ground on the system, which operates underground, at ground-level and on elevated tracks.

Broken Limbs

Metro didn’t describe the other people killed. Fifty of those hurt had “minor” injuries, Metro said.

“Clearly some have broken limbs,” said Brad Bell, a reporter for local station WJLA-TV, in a televised report from the site. “Their legs are being splinted. There is a long line of ambulances at the ready.”

The trains that collided were on the same track headed downtown. Both trains had six cars, according to Debbie Hersman of the National Transportation Safety Board, which will investigate. Metro trains have as many as eight cars.

The accident was the first in which a Metro customer was killed since 1982, when three people died in a derailment between the system’s Federal Triangle and Smithsonian stations in downtown Washington, Metro said. It was the second collision between two Metro trains.

The accident was the worst U.S. commuter crash since last year’s collision in Los Angeles between a Metrolink commuter train and a Union Pacific Corp. freight train that killed the Metrolink operator and 24 passengers.

Ran to Site

Laura Medina, 48, said she lives about a block from the accident scene and ran to the site, arriving before many of the rescue personnel.

“I’ve lived here for 25 years and never saw anything like that,” Medina said.

The two most recent transit accidents the NTSB board reviewed were on Boston’s Massachusetts Bay Transportation Authority, spokesman Peter Knudson said. The board, which determines the causes of accidents, doesn’t keep statistics about transit incidents, he said.

Metro’s trains run on five lines and carry an average of 987,000 passengers each weekday, according to the Washington- based public transportation association.

An underground collision on the Red Line in 2004 injured 20 people when an empty train rolled into a six-car train carrying passengers.

To contact the reporter on this story: Angela Greiling Keane in Washington at agreilingkea@bloomberg.net

Last Updated: June 22, 2009 20:56 EDT