A person has been hit by a train on the line between Chelmsford and Witham leading to the cancellation of rail services to and from London.
The train operator, Greater Anglia, is warning of travel disruption and delays until at least 1pm following the incident.
Replacement buses have been ordered to run between Witham and Braintree.
Services between Norwich, Ipswich and Colchester and London Liverpool Street will be affected.
Greater Anglia tickets are also being accepted on First Essex local bus routes 70, 71 and 100.