One witness said: "I just saw hundreds of people running.
"I was here and then everyone just ran, it was crazy.
"Police were just shouting at us all to get out, I have no idea what’s happened.
"I’ve never seen so many people running before."
To help minimise disruption to passengers, whilst the railway is closed Network Rail is also carrying out significant maintenance work between Watford Junction and London Euston
Ummm there's a huge police presence and a bomb squad at Euston station pic.twitter.com/LhikjX6gvK— katy (@haymaya_) August 29, 2017
British Transport Police initially said its officers were responding to a security alert at Euston train station.
They said: "The station has been evacuated. We will update when possible."
Eyewitnesses said there was a "huge police presence" and a "bomb squad" at the station as passengers fled the scene.
Virgin Trains said all lines were blocked due to the security alert at 7.40pm.
Police later revealed that an e-cigarette in a bag was behind the explosion at the busy train station in North London.
Bomb disposal and roads around Euston as far as Kings Cross pic.twitter.com/N1vl5xqKKI— Herts London News (@WatfordLondon) August 29, 2017
British Transport Police later said: “Officers are currently at Euston station responding to a security alert.
“We are investigating but there appears to have been a small contained explosion which is believed to have been caused by an e-cigarette which was in a bag at the station.
“No one is believed to have been injured.
“We were called at around 7.40pm.
“The station is currently evacuated whilst officers and search dogs check the area is safe.
“We are working with Network Rail to reopen the station as soon as possible.
“Thank you everyone for your patience.”
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