One woman has died and scores were taken to hospital after an underground train filled with smoke in the US capital Washington DC on Monday.
Passengers were left coughing and spluttering in darkness as the driver urged them on the tannoy system to "stay calm" and "not open the doors".
They were eventually able to evacuate the train and climb several flights of stairs in a vent shaft to ground level, where emergency vehicles were waiting.
One passenger, Jonathan Rogers, filmed this shocking footage of the train filling with smoke:
A report on the District of Columbia Fire Department (DCFD) website said Mr Rogers performed CPR on a woman for 20 minutes on board the train before she died.
The National Transportation Safety Board, which is investigating the incident, said the cause of the fire is not yet clear:
Mr Flangan said the southbound train had stopped for an unknown reason about 250 mtres (800 feet) beyond the L'Enfant Plaza station in downtown Washington.
In the video above, the driver can be heard urging passengers not to open the doors so that he can move the train "back to the platform".
A total of 200 people were evacuated from the tunnel with scores being evaluated at the scene, the DCFD said.
Footage showed passengers coughing on the street outside the subway station with firefighters giving some of them oxygen masks.
Some 84 patients were transported to local hospitals and two remain in a critical condition
The subway system, which operates in Washington and nearby Virginia and Maryland suburbs, is the nation's second-busiest in terms of passengers carried after New York City's subway network.