Passengers have been advised to avoid London Waterloo station all day after a train derailed outside the station.
The train partly left the tracks as it was pulling away from a platform at low speed at 05:40 BST, Network Rail said.
Three people were checked over by London Ambulance Service but nobody was taken to hospital.
Ten platforms are already shut as part of engineering works to enlarge the station's capacity.
Emergency services including police, paramedics and fire crews were called to the scene.
Photos shared by passengers on social media suggest the passenger train had struck an engineering wagon.
Chris Denham, a spokesman for Network Rail, told the BBC the partially derailed train had blocked three of the platforms so only very limited services could run.
"If you don't have to travel to Waterloo today, please don't," he said.
South West Trains said there would be a very limited service running to and from Waterloo "which is expected for the rest of today".
Many of the trains running have been cancelled or are are stopping or starting short of the station, the rail operator said.
Passengers are being advised to use alternative routes and have been warned other stations in the area will be "very busy" with the possibility of queuing systems being put in place.
The ongoing £800m engineering project at Waterloo will prepare the station for longer trains and provide space for 30% extra passengers during the busiest times of the day.
The station is usually one of the busiest in the UK, with an average of 270,000 journeys made to and from it each day.