Emergency services were called to a London Underground station after reports of an explosion on a train.
Pictures appeared to show an explosion in a bucket towards the rear of a train.
The incident occurred at Parsons Green Tube station earlier this morning.
Local reports said passengers suffered facial burns.
The Metropolitan Police said: “We are aware of an incident at Parsons Green Tube station. Officers are in attendance.”
British Transport Police said: “We’re aware of an incident at Parsons Green station. Officers are at the scene. The station is closed.”
Transport for London said it is “investigating an incident at Parsons Green“ and urged customers travelling between Wimbledon and Earls Court to use alternative routes.
A London Ambulance Service spokesman said: “We are on scene alongside the Metropolitan Police at Parsons Green.”
London Fire Brigade said they were called to the incident at 8.21am on Friday.
Natasha Wills, of London Ambulance Service said: “We were called at 8.20am to reports of an incident at Parsons Green underground station.
“We have sent multiple resources to the scene including single responders in cars, ambulance crews, incident response officers and our hazardous area response team, with the first of our medics arriving in under five minutes.
“Our initial priority is to assess the level and nature of injuries. More information will follow when we have it.”