A worker at Karlberg station says he saw a train roll into the station causing sparks to fly, and he then heard a sudden bang.
The Traffic Administration predict the power line will be repaired by 8 pm. Travellers are advised to use the Metro train system.
This major train disruption comes hot on the heels of Tuesday's track failure, which saw trains re-routed to avoid the south. "But now the trains that were diverted have been affected by this new accident," says Elina Yli-Torvi at train operator SJ.