Power was gradually being restored to Oahu this morning after most of the island was sunk into darkness for 12 hours or more, apparently due to a lightning storm.

As of 8:40 a.m., Hawaiian Electric Co. officials said about 182,000 out of 295,000 customers were back online as the company brought the island back on methodically to avoid overloading the system.

The blackout thrust Hawaii’s electrical generation problems into the international spotlight as the state’s most famous native son, President-elect Barack Obama, and his family were affected in their Kailua vacation compound. The home had emergency power and Heco officials said they sent a backup generator to the home last night.

Mayor Mufi Hannemann said at about 10:10 p.m. that Honolulu police had talked to Obama. “He said he is fine and he and his family are going to bed,” the mayor said on KSSK.

A media pool report this morning said Obama took his daily trip to the Semper Fit fitness center on the Marine Corps base Hawaii at Kaneohe.

 HECO spokesman Darren Pai said this morning that power is being restored from the Leeward side to the east. Electricity at all major hospitals has been restored, as well as the city’s Honouliuli Wastewater Treatment Plant. 

Pai said the company has not yet confirmed the cause of the islandwide outage, despite reports that a lightning strike may have caused it. 

“For those customers without power, we’re asking for patience,” Pai said. “We’re asking those with power to practice energy conservation while we get things online. This is going to help maintain stability on the grid.”

The lights started going out at about 6:30 p.m. during a rare electrical storm that apparently knocked out transmission lines from the Kahe and Waiau power plants. Within an hour, nearly the entire island was dark.

The outage closed stores at major retail outlets just after sunset, halting post-Christmas shopping a couple of hours early. Ala Moana Center was mostly reopened this morning.

Heco officials said last night that apparent lightning strikes triggered so-called “load shedding”—an automatic shutting down of power area after area on Oahu to prevent a catastrophic shutdown of the entire system. One plant, Kahe 4, was working for a couple of hours giving power to Makakilo and parts of Waianae. However that plant also went out about 8:30, making the blackout islandwide.

The outage started when transmission lines from Kahe lost power at about 6:30 p.m., which started a “tripping effect” that shut down different areas of the island.

John Cummings III, spokesman for the city Department of Emergency Management, said that as soon as the power went down, the city activated its Emergency Operating Center. Officials from Honolulu police, fire, Emergency Management Services, the Board of Water Supply and the city transportation gathered at the center with the mayor.

Officials asked the public to only call 911 for extreme emergencies. Emergency officials have been inundated with calls since the power went out. Fire officials responded to numerous calls of people stuck in elevators.

Although the outage occurred during a thunderstorm, the weather cleared up quickly over most of the island.

The outage closed stores at major retail outlets just after sunset, halting post-Christmas shopping a couple of hours early.

Highways were clogged as everyone tried to get home at once without stoplights to control traffic.

The blackout prevented this morning’s editions of the Honolulu Star-Bulletin from being printed and delivered, but an edition for limited distribution and street sales was expected later today.

Several Christmas weekend events were scuttled by the blackout, including a show by comedian Howie Mandel.

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The Associated Press contributed to this report.