The transit network in the nation's capital remained hobbled Tuesday morning after an electrical malfunction that filled a busy subway station with smoke, killing one woman and sending dozens of people to hospitals.
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.