An explosion on a London Underground train is being treated as a "terrorist incident", British police said. According to Al Jazeera. 
The Metropolitan Police said emergency services were called to Parsons Green station in west London at 8.20am local time (07:20 GMT) following reports of a fire on a commuter train.
A bucket wrapped in an insulated bag caught fire on a packed London subway train on Friday, sending commuters stampeding in panic at the height of the morning rush hour. Police said they were investigating it as a "terrorist" attack.
"Deputy Assistant Commissioner Neil Basu, the senior national coordinator for CT policing, has declared it a terrorist incident," the Metropolitan Police said in a statement.  
Photos taken inside a District Line train show a white plastic bucket inside a foil-lined shopping bag. Flames and what appear to be wires emerge from the top. London ambulance service said they had sent multiple crews to the Parsons Green station, and 18 people were hospitalised, though none had life-threatening injuries.
London Transport said services were cut along the line amid reports on social media of the station's evacuation.