An electrical substation has “blown up” leaving homes without power.
Firefighters were called to Churchdale Road, Eastbourne, after residents heard a loud bang on Friday evening at 6pm.
An East Sussex Fire and Rescue spokesman said the substation had “blown up” and that UK Power Networks were called.
A spokeswoman said: "UK Power Networks engineers are working as quickly as possible to restore electricity supplies to 90 customers in the Churchdale Road area of Eastbourne.
"A fault at an electricity substation interrupted supplies to 483 properties at 6pm last night. Engineers rerouted power to the majority of customers in stages by midnight.
"We are sorry for any inconvenience caused and can assure customers that work is progressing to reconnect the remaining supplies."
Lightning is not believed to be the cause. An investigation is ongoing.