The transit network in the nation's capital remained hobbled Tuesday morning following an electrical malfunction that filled a busy subway station with smoke, killing one woman and sending dozens of people to hospitals.
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The National Transportation Safety Board was investigating the accident, which happened at the beginning of the Monday afternoon rush hour and led to the first fatality on Washington's Metro system since a 2009 crash that killed eight passengers and a train operator.
NTSB investigator Michael Flanigon told reporters late Monday night that an electrical "arcing" involving the high-voltage third rail led a train to stop in a tunnel and quickly filled the tunnel with smoke. An arcing occurs when electricity from the third rail comes into contact with another substance that conducts electricity, such as water.
While there was water in the tunnel, Flanigon said the cause of the arcing was not yet known.
"The third rail is high-voltage direct current, and if that current starts arcing to another conductor that it is not designed to connect with, you get a flash," Flanigon said. "In certain cases, that arc can start sort of feeding on itself, and it actually generates gases that are more conductive."
Witnesses described a chaotic scene aboard the train as passengers tried to escape the smoke, and many passengers left the train on their own before emergency responders arrived on the scene, Flanigon said. In addition to the woman who died, whose name had not been released as of Tuesday morning, at least one other passenger was in critical condition at a local hospital. Eighty-four people were taken to hospitals, most with smoke inhalation, authorities said.
"It started to get scary pretty quick," passenger Jonathan Rogers told The Washington Post. "People started praying. Smoke was coming in pretty steadily."
The accident occurred around 3:30 p.m. Monday on a Virginia-bound yellow line train that had just left the L'Enfant Plaza station in downtown Washington, one of the system's busiest stations. The train stopped about 800 feet beyond the platform, and the arcing occurred roughly 1,000 feet beyond the train, Flanigon said. The train did not derail, and there was no fire, he said.
The yellow line remained shut down Tuesday morning, and the system's orange, blue and silver lines were on a reduced schedule. Service on the green and red lines was normal.
The Metrorail system, which connects downtown Washington with the Maryland and Virginia suburbs, carries an average of 721,000 passengers each weekday.
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