Two people are being questioned about the kidnapping of a British photographer in Syria.
The man and woman were arrested at Heathrow Airport. Scotland Yard is investigating whether one of those arrested is an NHS doctor.
Ronke Phillips discussed the latest developments with Nina Hossain.
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The 24-year-old was unarmed and the incident is not being treated as terror-related.
Some platforms have been taken out of service with disruption expected to continue until the end of the day.
The Met Office has extended its weather warnings for snow and ice to cover vast swathes of the country, including London and the South East.