Pictures appearing in the wake of the incident show emergency services working on the scene and people fleeing it, causing stampede. The Parsons Green tube station was closed and train services on the line were halted. Police called on people to avoid the area near the station.
"We were called at 8:21 a. m. and we have information there was a fire on a train eastbound at the platform at Parsons Green. We have got two fire engines there," a London Fire Brigade spokeswoman said as quoted by The Sun newspaper.
A picture of the alleged container has appeared on social media. The object reportedly went off toward the rear of the train.
The Metropolitan Police, the London Ambulance and the London Fire Brigade had arrived at the underground station.
We're aware of an incident at #ParsonsGreen station. Officers are at the scene. The station is closed. More information as we get it.— BTP (@BTP) 15 сентября 2017 г.
The incident has not been classified a terrorist attack.
District Line from the pic I've seen looks a lot more like a Lithium Battery fire than some sort of planned terrorist act #ParsonsGreen— Tony McAlinden (@mackanory) 15 сентября 2017 г.
People took to Twitter to express their worries and hopes that the incident had not left anyone dead.
Ffs leave my city alone. Thoughts are with all those involved #parsonsgreen— Olly 😼 (@OllieMogs) 15 сентября 2017 г.
I hope whatever has happened at #ParsonsGreen isn't too serious. Thoughts go to all involved.— Nicky Green (@Nickyquin) 15 сентября 2017 г.
The UK capital has recently suffered a string of terrorist attacks.
In early June, a vehicle hit pedestrians on London Bridge. The vehicle with three suspects continued to drive from London Bridge to Borough Market, after which the suspects left the vehicle and carried out a stabbing attack at the market. The attackers were confronted by the police and shot dead within minutes.
In late March, 4 people were killed and many were injured after a vehicle drove into a crowd on London’s Westminster Bridge near the UK Parliament building. One man was later shot by police after he stabbed an officer inside the Parliament compound.