Flames engulfed one carriage and raced along a train on a west London route to Parsons Green, forcing passengers to trample others as they rushed for an exit, an eyewitness told Reuters.
The man said people were trampled on when they fled the train after hearing a whoosh and seeing flames race towards them. He said he did not hear a bang after police rushed to an incident at the station at Parsons Green.
"I just heard a kind of whoosh. I looked up and saw the whole carriage engulfed in flames making its way towards me," he told Reuters, adding that the train was packed with people.