London North Eastern Railway tweeted that several services between London King's Cross and Leeds had been cancelled.
Cancelled services include the 5.14pm, the 5.48pm and the 7.03pm service from London King's Cross to Leeds.
The incident has caused several hours of delays to services through Wakefield and Leeds, with services cancelled since 1.30 this afternoon.
It is not clear how long disruption is expected to last.
Those travelling to Peterborough, Doncaster, Wakefield Westgate and Leeds
For alternative travel arrangements, see the London North Eastern Railway Twitter.