A 64-year-old woman fell onto the tracks at Swiss Cottage Tube station as a train pulled into the platform on Wednesday.
The London Air Ambulance landed behind Hampstead Theatre as emergency services sped to the scene.
The woman is believed to have fallen between two carriages as a Jubilee line train approached the platform.
A tearful and shaken Lizzie Delaney, who was on her way to work from her home in Willesden, said: “I was standing behind her and I don’t know if she jumped or fell, but she got stuck between two carriages – it was awful to watch.”
Fire engines, British Transport Police and ambulance crews all descended on the station in Avenue Road at 9.05am.
The woman was taken to hospital to be treated for minor injuries.
A spokeswoman from London Ambulance Service said the woman had not been hit by the train.
The line was reopened after 9.30am.
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