Amtrak service between Philadelphia and Washington DC has been restored following overhead wire damage but many trains are still delayed.

Crews make repairs on Amtrak overhead wires in Maryland (@Amtrak via Twitter)

Riders can expect extensive delays as final repairs are made and service restored to a second track. The railroad said the cause of the damage to wires in Cecil County, Maryland is still being investigated.

Twitter users are expressing frustration at the situation as information about specific delays is not being offered.

The Acela Express, Northeast Regional and local commuter lines including SEPTA and MARC were affected by an earlier suspension of service.

The Associated Press contributed to this report