Lines have now reopened subject to delays after a Kings Cross to Sunderland service collided with a number of cows, killing 11 of them.
The 9.38am Grand Central service to Wearside struck a heard of cattle on the track at Huntingdon, in Cambridgeshire, earlier today.
Great Northern Rail tweeted that 11 cows were confirmed dead, while a further 15 remain missing.
As a result, all lines, running north between London Kings Cross and Peterbrough were blocked, cancelling a number of services, including the 13.45 service to Sunderland.
Grand Central said in a statement: “Due to animals on the railway between Peterborough and London Kings Cross all lines are blocked. Train services to and from these stations may be subject to disruption on all routes.”
The train operator tweeted that all lines had reopened shortly after 3pm.