Rail replacement buses are running between Pitsea and Grays - with journey times extended by up to an hour.
The disruption is expected to last until lunchtime.
More top news
Eight fire engines and 60 firefighters are working to try and put out a large fire at a cafe in Fulham. One person has been injured.
A coffee shop in Fitzrovia is allowing customers to buy discounted hot drinks and pass them on to a homeless person
A man has been jailed for seven years for raping a woman after she fell asleep on a night bus in Hampstead