Updated from 12:43 a.m. EDT

WASHINGTON -- The death toll climbed to nine in a rush-hour collision between two Metro trains north of Washington on Monday, CNN affiliates reported, with scores more injured.

WJLA and WUSA attributed the information to officials for the Washington Metropolitan Area Transit Authority, CNN reported.

It was reported earlier by the

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Associated Press

that one Metro transit train smashed into the rear of another at the height of the capital city's Monday evening rush hour, killing at least six people and injuring scores of others as the front end of the trailing train jackknifed violently into the air and fell atop the first.

Cars of both trains were ripped open and smashed together in the worst accident in the Metrorail system's 33-year history. District of Columbia fire spokesman Alan Etter said crews had to cut some people out of what he described as a "mass casualty event." Rescue workers propped steel ladders up to the upper train cars to help survivors scramble to safety. Seats from the smashed cars spilled out onto the track.

A Metro official said the dead included the operator of the trailing train. Her name was not immediately released.

The crash around 5 p.m. EDT took place on the system's red line, Metro's busiest, which runs below ground for much of its length but is at ground level at the accident site near the Maryland border in northeast Washington.