A derailed train has blocked lines on a major route between England and Scotland, Northern Rail has said.
An engineering train came off the track near Carnforth, Lancashire, affecting services by Northern, TransPennine Express and Virgin Trains.
Disruption was expected to last throughout the day.
The National Rail Enquiries website said: "An engineering train has derailed between Lancaster and Oxenholme Lake District and this is causing disruption to trains between Preston and Carlisle / Windermere."
Bus replacement services were expected to be brought in.