Commuters were facing rush hour delays on Wednesday after a man was seriously injured on the tracks at Westminster station.
The air ambulance was scrambled and landed in Parliament Square as part of the emergency response.
British Transport Police (BTP) and fire serves were also on the scene.
A BTP statment said: "Officers were called to Westminster Underground station at 14.31pm today following reports of a casualty on the tracks.
"Paramedics also attended and a man is being taken to hospital with serious injuries.
"This incident is not being treated as suspicious."
Police taped off the station as paramedics tended to the stricken man. A line of emergency vehicles with flashing blue lights pulled up in the shadow of the Houses of Parliament.
Glen Hedges who was near the station said: "It was chaotic there were emergency services everywhere. A helicoper landed nearby. We wondered if it was a terror alert or something."
More to follow.
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