Winds with gusts up to 70 mph yesterday blew over trees, utility poles and power lines, knocking out power to thousands of residents across O'ahu.

Hawaiian Electric Co. crews restored power to tens of thousands of customers, and planned to work through last night and this morning to restore power to others who remained without electricity. As of 10:50 p.m. yesterday, about 8,000 customers did not have power, said HECO spokeswoman Barbara Heckathorn.

At one point yesterday morning, more than 45,000 customers were without electricity.

Winds brought down 34 utility poles on O'ahu, a majority along the Leeward Coast near Nanakuli, and the North Shore.

Pai said people in these areas should expect a lengthy outage, but he could not say for sure how long.

"The work there that has to be done is pretty extensive," replacing poles in Nanakuli, HECO spokesman Darren Pai said. "We understand that they have been without power for a very long time and we appreciate their patience and we're asking them to be a little more patient. We're working as quickly as we can, but we want to make sure that the repairs are made properly."

At least 16 poles fell along one stretch of Farrington Highway, including some that had been installed a little more than a year ago. In March 2006, strong winds toppled more than a dozen poles, leading HECO to inspect about 100 in that area.

Major outages also were reported in Central O'ahu, including parts of Mililani and Wahiawa; portions of Waimanalo, Kailua and Kane'ohe; 'Ewa Beach; and parts of Downtown in the Nu'uanu area. Pockets of blackouts also were reported in other communities.

Pai said it was difficult to determine how many customers lost power throughout the day.

"We do a restoration and then another problem pops up. It's so fluid that I'm afraid I can't really give you a new number," Pai said.

He said the repair and restoration work may seem to take a long time but that safety is HECO's top priority.

"We want to work as safely as possible because we don't want to make a bad situation worse. We don't want to rush through a job just for the sake of getting to another one," Pai said.

Reach Curtis Lum at culum@honoluluadvertiser.com.