King's Cross Station was evacuated today after Standard Liege fans set off flares.
Thousands of fans from the Belgium club have travelled to London ahead of their Europa League clash against Arsenal tonight.
Footage shows supporters walking through a cloud of red smoke inside the station before congregating outside.
Police arrived on the scene after reports of an emergency broke when tube commuters were told to leave the area just after 1pm.
The station re-opened shortly after 3pm.
One witness said: "These men have just shut down kings cross station, throwing fire crackers and generally freaking a few people out. Jumpers say 'red fanatics'"
Another wrote: "Sirens going off at Kings Cross underground. Reported emergency. People being asked to leave #London."
"Love to be evacuated out of kings cross station because grown men can't behave themselves (especially) when they affiliate themselves to a group of other men who kick a spherical object around a patch of grass," added a third witness.
TFL tweeted: "King's Cross Station - Closed due to a fire alert. All trains non stopping"
At just before 15.15 the Victoria Line Twitter posted: "King's Cross St.Pancras: The station has re-opened and trains are now running normally.
We're sorry if the closure disrupted your journey. This was due to an earlier fire alert."
A spokesman for British Transport Police said: "Officers were called to Kings Cross Underground station at 1.30pm today (03/10) following reports of large numbers of football fans setting off flares.
"The station has been closed while the London Fire Brigade respond, and the football fans are being dispersed by officers."
Many were quick to praise the TFL staff and Metropolitan Police for their quick response to the disruption.
One tweeted: "Got off the Victoria Line to be evacuated out of Kings Cross Station immediately because football supports are letting off gas bombs in the station and outside... kids crying outside & people trying to rush... it was manic... luckily police were there to handle the situation well."
