A broken down train between Sudbury and Marks Tey has blocked rail lines.
Services between the stations have been disrupted this morning (Tuesday).
A Greater Anglia spokesman said: “Following a broken down train between Marks Tey and Sudbury, all lines will be reopened shortly.”
Services will restart with the 10.01am train from Sudbury.
Major signalling problems, thought to have been caused by the theft of wires along the track near Chelmsford, have also caused delays and cancellations between Witham and Shenfield, further affecting Sudbury passengers into London.
Greater Anglia is currently advising customers to avoid travelling.