Parts of St Albans were plunged into darkness this morning when a power cut hit hundreds of homes.
UK Power Network engineers are currently in the area trying to restore power to 770 customers.
The cause of the power cut, which happened at 8.21am this morning, is being investigated.
A further 519 customers were originally affected but their power was restored just before 9.30am.
UK Power Network has apologised for the inconvenience caused.