Train travel has been disrupted between Cambridge and King's Lynn.
Great Northern train services to and from Downham Market have been particularly disrupted as a result of problems with overhead wire damage between Cambridge and King's Lynn.
The disruption is expected to continue until 3pm on Tuesday, July 30.
A spokesperson for Govia Thameslink Railway said: "Shortly after 9:15am we received reports of damage to the overhead wires between Ely and King's Lynn.
"Specialist network rail engineers, British Transport Police and other operatives are on site.
"Great Northern are planning to run a train shuttle service between King's Lynn and Downham Market, however there is a freight train blocking the line at Downham Market.
"Some buses have been arranged but these are limited and are not enough to cope with passenger numbers."
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