Much of Auckland's waterfront was plunged into darkness for an hour tonight after a loud bang was reported from a switching box off Viaduct Harbour.
Electricity distribution company Vector reported supplies cut to 1866 premises, including traffic lights, which sent police rushing to key intersections to go on points duty.
Auckland Transport said traffic signals were knocked out from Fanshawe St and all the way along Customs and Quay streets to Parnell, although the main motorway entry to the central city at Victoria Park was unaffected.
Most of the Viaducts' bars and restaurants were evacuated following the outage and one person was released by firefighters from a lift in Shed 24, Princes Wharf.
The police said they were unaware of any other major problems caused by the blackout, but had sent officers out to help to control the traffic.
But by 7.50pm, about an hour after the cut, Vector reported that electricity had been restored to all except 19 customers.
Auckland Transport said minutes later that all traffic signals were back in action.