Police have released a photograph of the 16-year-old who was stabbed to death in Pimlico.
Hani Hicham Abou El Kheir was taken to hospital on Sunday evening but died later that night.
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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.