An engineering train has derailed in south London causing the closure of the Gatwick Express service.
The train partly left the tracks between Victoria and Clapham Junction overnight.
No Gatwick Express trains are running while Southern has warned that its services will be “severely reduced”.
Network Rail said it was working to remove the train but passengers should “travel later in the day if possible” or seek an alternative route.
A Network Rail spokesperson said passengers should travel “via London Bridge or London Blackfriars as trains will be delayed, diverted or cancelled”.
Train tickets for Southern and Gatwick Express services are being accepted for reasonable routes on other services.
Disruption is expected to last throughout Tuesday.