A 15-year-old girl was removed from a plane at Heathrow Airport over concerns she was traveling to Syria to join up with Islamic terrorists earlier this month.
The teenager was reported missing from her home in Tower Hamlets, east London, before attempting to leave the country.
Metropolitan Police said the girl has since returned to her family after being taken off the flight heading towards Istanbul in Turkey on 6 December.
Police said they probably "saved the life" of the girl by stopping her travelling to Syria to join up with militant groups such as the Islamic State (IS).
It is reported the plane was already setting off on the runaway when officers arrived.
A Met source told the Evening Standard: "The plane was taxiing down the runway but we managed to turn it round. This was a big decision to take because of all the disruption it caused. But we had to stop her going. It has probably saved her life."
A spokesperson added: "On Saturday 6 December, police received reports of a 15-year-old girl from Tower Hamlets missing from home. Officers were able to locate her and she has since returned home safely."
However, one 15-year-old girl who was travelling on the same day did manage to leave the country before police could intervene.