Train services between Exeter St Davids and Barnstaple have been suspended due to flooding on the line at Crediton.
Replacement buses are currently conveying passengers after all trains were stopped at around 1pm.
Several First Great Western services have been affected. On Twitter, the rail giant said: "Due to flooding between Crediton and Barnstaple train services running through these stations may be cancelled or delayed by up to 20 mins."
Stations affected include; Newton St Cyres, Crediton, Yeoford, Copplestone, Morchard Road, Lapford, Eggesford, Kings Nympton, Portsmouth Arms, Umberleigh, Chapelton and Barnstaple.
A spokesperson for National Rail said replacement buses would be in action until further notice, before later adding that disruption is expected to continue until at least 4.15pm.