A police helicopter was scrambled as part of a search for a 15-year-old girl who ran along railway lines in Romford on Wednesday night.
Police say that the teenager had run away from King George Hospital in Goodmayes, after trying to harm herself, and boarded a train at around 11.20pm.
At Romford she got out and started walking along the track headed towards Shenfield.
Officers found her close to Asda at 12.15am and took her back to hospital.
There were minor delays on three trains as a result.
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