Passengers travelling between London St Pancras International and Bedford are experiencing delays of up to an hour this afternoon (Thursday, April, 17).
A person was hit by an East Midlands train between Flitwick and Bedford at 12.30pm.
All lines were immediately closed pending attendance and investigation by the emergency services.
Three of the four lines reopened at 13.40pm.
A First Capital Connect spokesperson said: “Because of severe train and driver displacement there are still delays of up to 60 minutes on the Thameslink route.
“Rail replacement buses are running between Luton and Bedford, calling at all stations. We apologise for the inconvenience.”
Delays are expected to last until 6.30pm.