HONOLULU - THE island of Oahu, including the resort where President-elect Barack Obama is vacationing, was hit by a power blackout on Friday, possibly caused by a lightning strike, authorities said.

Eyewitnesses said it appeared electricity in Mr Obama's holiday compound was knocked out and workers were hurrying to set up an emergency generator.

An electricity company spokesman said the entire 1553 sq km island, which is home to around 900,000 people, was affected.

'We lost the last generator ... The whole island is now without power,' said spokesman Peter Rosegg.

Traffic was snarled on major Honolulu roads.

Honolulu Mayor Mufi Hannemann told KSSK radio station it would be at least 12 hours before power was restored. Rosegg said it might be considerably longer.

A state transportation official told local radio planes were still landing at the Honolulu International Airport but takeoffs were suspended.

Residents said this was the largest power outage since an earthquake caused a major blackout in October 2006.

A civil defense official said it was possible a lightning strike on a transformer had caused the outage. A strong thunderstorm moved over the island just before the power failure. -- REUTERS