WATCH: Boris Johnson urges public to 'keep calm' following London terror attack
Boris Johnson has urged the public to "keep calm" following the terror attack on a Tube train this morning.
An improvised explosive device detonated at Parsons Green station in south west London at approximately 8.20.
Eighteen people have been taken to hospital, most for treatment to "flash burns" sustained in the attack.
Theresa May has returned to Downing Street from her Maidenhead constituency to chair a meeting of the Government's emergency Cobra committee.
Speaking shortly after the incident, Foreign Secretary Mr Johnson said: It's important not to speculate at the moment, but obviously everybody should keep calm and go about their lives as normally as they possibly can."
In a statement, the Prime Minister said: "My thoughts are with those injured at Parsons Green and the emergency services who, once again are responding swiftly and bravely to a suspected terrorist incident."
The terror attack is just the latest to hit the UK this year, with outrages also taking place at Westminster and Tower Bridge in London, and at an Ariana Grande concert in Manchester.
It is not known whether the Parsons Green attacker remains at large, but President Donald Trump appeared to suggest in a tweet that the perpetrator was being watched by the police.