Scotland Yard says an explosion on a Tube train at Parsons Green, in west London, is being treated as a terrorist incident.
Witnesses say they saw a flash and heard a blast – emergency crews are now dealing with the incident at Parsons Green station in west London.
Pictures have been posted online, showing a burning plastic container in a carriage.
Several people have been hurt – with reports of some commuters suffering facial burns and others being injured in the rush to get out.
Ambulance crews have sent a hazardous area response team to the incident.