The stability of O'ahu's power grid is under scrutiny again after the second islandwide blackout in two years triggered a water shortage, left people trapped in elevators, shuttered major shopping centers and raised concerns about the well-being of the next president of the United States, who is vacationing in Kailua.

Gov. Linda Lingle initially was worried that the White House press pool following President-elect Barack Obama's family vacation would generate worldwide negative publicity for Hawai'i as its No. 1 industry — tourism — continues to struggle.

The negative press did not materialize, Lingle said. But hundreds of visitors who arrived Friday night to a blackened Honolulu International Airport were told that their vacations coincided with a power outage and had to use old-fashioned stairs to deplane because the electric jetways could not operate.

Nearly 24 hours after the blackout hit, some 11,000 Hawaiian Electric Co. customers remained without power last night and HECO officials still could not precisely identify the cause.

"Oh, man, am I mad," said Leonard Oh, 61, who was born and raised on O'ahu. "Angry? I've never been in a place like this that has a major power outage every year."

Two homes in Kane'ohe and one in Kapolei were destroyed or heavily damaged by fire yesterday, but fire officials could only say for certain that one of those was related to the outage.

The two homes in Kane'ohe ignited shortly after power returned to their neighborhoods, one because of a stove that turned back on, fire officials said.

By late afternoon, 282,000 of HECO's 293,000 customers — more than 95 percent — had their power restored. Pockets of customers remained without power in Kalihi, Waikele, Manoa, upper Makiki and Kunia.

The Honolulu Board of Water Supply had its own blackout-related problem: The lack of power meant water could not be pumped into the city's reservoirs. So an unknown number of customers from Hawai'i Kai to Salt Lake lost their water service yesterday, spokeswoman Su Shin said.

Both HECO and the Board of Water Supply are encouraging people to conserve energy and water use even into today by taking such measures as turning off automatic sprinkler systems and delaying washing clothes.

"The people who have power think everything's back to normal, but it's not," Shin said.

The outage also knocked out the city's ultraviolet disinfection units at its Wahiawa and Sand Island wastewater treatment plants, sending 30,880 gallons of partially treated sewage into the Wahiawa Reservoir and an estimated 1 million gallons of partially treated sewage out through Sand Island's deep ocean outfall, according to the city.

Warning signs were posted in the areas.

LIGHTNING SUSPECTED

While the exact cause of the blackout was still under investigation, witnesses reported seeing lightning strikes near four HECO transmission lines — three emanating from the Kahe Power Plant in Wai'anae and one from the Waiau Power Plant in Pearl City.

All four lines went down within 20 minutes of each other, triggering a chain reaction that eventually shut down all six generators at the Kahe Power Plant and two generators at Waiau, HECO spokesman Darren Pai said.

HECO has been through a similar drill before.

On Oct. 15, 2006, separate 6.7 and 6.0 magnitude earthquakes centered off the coast of the Big Island knocked out power to more than 291,000 HECO customers on O'ahu for about 15 hours. In the aftermath, about 1,400 customers filed claims for damage ranging from spoiled food to damaged electronic equipment.

"They keep having these power outages because they don't know how to troubleshoot it," said Clarence Bubba Piena, 48, of Kane'ohe. "They're supposed to know what's coming and be prepared for it. It's all about getting back to the basics."

HECO officials said their initial goal Friday and yesterday was restoring service to all customers, rather than searching for the cause.

Lingle yesterday praised HECO's top officials for communicating better with her and state civil defense than during the 2006 island-wide power outage that caused traffic gridlock and confusion.

Two years ago, communication between HECO and state civil defense "was not as robust," Lingle said.

"That was very different this time. ... In 2006, we all should have done a lot better, and we did do a lot better this time."

HANGING LOOSE

Communication with Hawai'i's visitor industry also was much improved since 2006, Lingle said.

An after-action review of the outage involving HECO, the state consumer advocate and state Public Utilities Commission will be conducted shortly, Lingle said.

In the first three hours after the power went out Friday night, Honolulu firefighters rescued more than 42 people stranded in elevators and helped 73 others, including people on electric-powered ventilators who needed to be transported to a hospital.

For the most part, drivers behaved calmly and treated blackened intersections properly as if they were four-way stops.

Lingle praised police officers who calmly managed busy intersections.

"I do give a lot of credit to the quick response of the police department," she said.

Even would-be criminals seemed to mind themselves, because there were no reports of major crime.

"Everybody seemed to be obeying the rules very well," Lingle said.

Lingle was celebrating the Jewish sabbath Friday night at a home in Kahala when the power went out around 7 p.m. Because of the Hanukkah season, the home was decorated with candles and the dinner party continued, Lingle said.

"Our host had said it was something that occurred fairly regularly in their neighborhood," Lingle said.

Then a member of Lingle's security detail received a call from his wife that power also was out in Kailua.

Lingle's staff called state civil defense for a more complete report and the governor headed to the civil defense headquarters inside Diamond Head at around 8:30 p.m.

TOURISTS RAMBLE AROUND

Waikiki had fallen into darkness and thousands of tourists descended from their high-rise hotel rooms only to mill about, uncertain what to do at the powerless epicenter of Hawai'i's tourism industry.

At the ABC Stores location on Ala Moana Boulevard, sandwiched between the Ilikai hotel and the Hilton Hawaiian Village's Kalia Tower, customers waited for up to 90 minutes as people were let in two at a time.

Store manager Emerson Tuppil immediately jumped into emergency mode. He and another employee immediately shut the doors and reopened with a sign on the door telling people to please wait their turn to get in.

Tuppil led people into the store with a lantern. An emergency-power light was working above a cashier's machine, which also was operating.

"We have enough (generator) power for the cashier," Tuppil said.

Most customers were tourists staying at nearby hotels who were looking for sandwiches, snack foods and soft drinks.

Among them was Dwight Winters, of Camarillo, Calif., who was staying at the Hilton Hawaiian Village's Tapa Tower.

Asked what was on his shopping list, Winters replied, "Sandwiches, cups, bread."

"These things just happen," Winters said.

Throngs of hotel guests and restaurant patrons hung out in the lobby and on the pool deck of the Ilikai hotel as fire alarms blared for at least an hour after the power died.

But most visitors appeared calm and even enjoyed the evening.

Chris and Becca Pound of Tulsa awoke at 4 a.m. Oklahoma time to make the 12-hour trip to Honolulu. They had just unloaded their luggage in their room on the 25th floor of the hotel and were stepping out of the elevator to go to dinner when the outage hit.

At least, Chris Pound said, "The weather is nice."

LAID-BACK IN LINE

Island residents, for the most part, took the outage in stride and some turned the blackout into opportunities for family time.

At the Beretania Street Foodland, about 100 people were lined up around 10 p.m. as groups of 25 were allowed to enter every 10 minutes or so. A store employee used a bullhorn to announce that all batteries and flashlights had been sold out, and that no perishable food was for sale.

"What about beer?" yelled one customer outside.

The store worker replied, "Yes, we've got plenty of beer, and ice."

At the Times Supermarket in Kahala, a long line formed as workers let limited numbers inside — until the store's generator ran out of fuel around 9:30 p.m.

Michelle Ho'okano and her family drove all the way from 'Ewa Beach looking for something to eat. They grabbed bread, lunch meats, drinks and chips and ate their dinner in the bed of their truck.

"We just had to find someplace to feed the kids," said Ho'okano, who was with her five young children and a neighbor's daughter.

At the Whole Foods in Kahala, dozens of people gathered to get a hot meal. Scott Wehner, 43, headed for the supermarket from Kailua after hearing on the radio that it was still open.

"The food is great," he said. "Everybody's calm."

Kelly Simpkins of Kaimuki sat outside the Whole Foods store having wine and cheese with friends.

"It's very calm," Simpkins said.

More than 100 people crowded 'Ewa Beach's two shopping centers searching for food, candles, batteries and the camaraderie created by shared circumstances.

At the 'Ewa Beach Star Market, a backup generator at the shopping center offered partial power.

People stood patiently in line while children ran around with flashlights and glow sticks. One group of shoppers turned the corner of the McDonald's parking lot into a fireworks show before security guards chased them away.

Louana Akina was at home playing the video game Rock Band: World Tour with her family when the lights went out at about 7 p.m.

"I feel lost," Akina said. "Hopefully they can get the power up and running. We'll play board games by candlelight until then."