Commuters are facing long delays after overhead wire problems resulted in train services being cancelled or delayed.
Services running to and from London Liverpool Street to Norwich, Ipswich and several Essex, external stations have been affected.
The cause was a fault with the wires between Shenfield and Chelmsford, blocking the line towards Colchester, Essex, according to Greater Anglia.
Network Rail staff are on site and will have the problem resolved as soon as possible, a spokesperson for the train company said.
