Some areas in Northland are running on backup generators, after a major transmission tower fell in Kumeu, in Auckland's northwest

Transpower says a second circuit's also down due to scheduled maintenance.

Thousands of people in the region don't have electricity and it's unclear when it will be back.

Whangarei Mayor Vince Cocurullo says pump stations, water, sewage, and the hospital are on backup generators.

He says patients coming in for treatments like chemotherapy can expect delays.