Police are investigating an incident on a London Underground train, amid reports of an explosion.
Scotland Yard said it was aware of the incident at Parsons Green station and officers were in attendance.
Firefighters from a number of stations, including Wandsworth, Chelsea and Hammersmith, are at the scene.
The ambulance service said it had sent a hazardous area response team to the incident.
The authorities said there was no service between Earls Court and Wimbledon on the District Line.
One commuter on Twitter said the driver had announced a train at Parsons Green had put in a mayday call.
Another person tweeted: “Everyone is screaming running off trains.”
Media technology consultant Richard Aylmer-Hall, 53, who was on the train, told Sky News: “There were a few crush injuries on the stairs.
“People got squashed and crushed going down the stairs. Police evacuated everyone from the scene pretty quickly.
“There was screaming, pushing and shoving – it was a like there was a terrorist on the loose with a gun or something – lots of people were in tears. When it was all over lots of people were being comforted and looked after.
“It was total chaotic panic. A lady who had been on the same carriage as the device described it going off – a puff of smoke and flames coming out of it.”
Ed Johnson, who was near Parsons Green, told Sky News: “I saw lots of worried faces and great concern.”
Natasha Wills, of London Ambulance Service said: “We were called at 8.20am to reports of an incident at Parsons Green underground station.
Source: Sky News