Update: police are treating the incident as a terrorist attack.

There are reports of an "explosion" at Parsons Green tube station in south-west London. Metropolitan Police have issued a statement saying that they are "aware" of the incident. Police and emergency services are currently at the scene. https://twitter.com/metpoliceuk/status/908597086924525568 The London Ambulance Service has confirmed that people have been injured. They are currently assessing "the level and nature" of the injuries. https://twitter.com/Ldn_Ambulance/status/908603264949727232 Social media reports indicate that an "explosion" occurred on the train. Passengers were then seen fleeing the station. https://twitter.com/RRigs/status/908594792816349184 https://twitter.com/garthserg/status/908596986567421952 https://twitter.com/EmmaStevie1/status/908595323777486848 Police have confirmed that they are treating the incident as a terrorist attack. https://twitter.com/metpoliceuk/status/908620962987433984 British Transport Police have said that Parsons Green station has been closed. Commuters have been urged to use alternative routes. More to follow.