Rain and wind pounded O'ahu yesterday, trapping people in flooded cars, ripping off roofs, unleashing mud, trees and boulders, and closing dozens of schools — triggering a scramble for childcare by parents.

Despite a flurry of 911 calls between 4 a.m. and noon to help everyone from swimmers in danger to stranded drivers, no serious injuries were reported.

Some 13,900 Hawaiian Electric Co. customers went without power for much of yesterday. By early evening, 160 HECO customers remained without service in scattered pockets of O'ahu, spokesman Darren Pai said.

Flooding was most common in Wahiawa, Wai'anae, Waialua, La'ie and Hau'ula.

More rain is expected today.

Even if the skies dry out, yesterday's drenching saturated the ground to the point that the danger of flash floods could remain for a couple of days, said John Cummings, spokesman for the city's Department of Emergency Management.

Some people who slogged their way out of flooded homes compared the severity of yesterday's storm to the 40 days of continuous rain that fell in 2006, the New Year's Eve flood of 1988 and even to Hurricanes 'Iwa (1982) and Iniki (1992).

"This is the worst I've ever seen," said Gerene Woodward of Makaha, who yesterday took her two children to an American Red Cross shelter in Wai'anae District Park — one of five emergency shelters that quickly went up in the Leeward and North Shore areas.

Cummings would not go quite that far but said, "This was an unusual event because the rain came in very, very quickly. It was like a big bucket of water just opened up over O'ahu."

Some areas were hit by as much as 14 inches of rain in 12 hours as a strong low pressure system arrived northwest of the state, the National Weather Service said.

A gauge in Kane'ohe showed 3.12 inches of rain falling per hour yesterday morning — something forecast to happen just once every 22 years. A gauge in Poamoho measured 3.84 inches of rain an hour, which forecasters predict happens just once every 31 years.

The city closed the Honolulu Zoo, municipal golf courses and its five botanical gardens. Other major attractions, such as the Polynesian Cultural Center, USS Arizona Memorial and Diamond Head State Monument, also shut down.

At one point yesterday morning, state Department of Transportation director Brennon Morioka asked drivers to stay off streets and highways, many of which were blocked by mudslides, flooding and cars damaged by falling trees.

"If they don't have to be be on the roads, please stay at home or stay at work until this clears up," Morioka said. "It'll be safer and easier for our guys and the city guys to do our jobs."

OFFICERS CLEAR PALI

Some highways, such as the Pali, had no traffic signals or street lights working during part of the morning commute.

Problems on the Pali could have been much worse, said Police Maj. Kurt Kendro, who is in charge of the Kalihi substation.

He was stuck in town-bound traffic on the Pali that was blocked by one fallen 60-foot tree and a couple of smaller ones.

Only later did Kendro learn that traffic was allowed to flow again because seven of his officers at the start of their 7 a.m. shifts decided not to wait for busy DOT road crews.

Instead, they tied a rope to a patrol car and to the trees while the other officers pushed and dragged the trees off the road.

"It was right at the peak of the commute," Kendro said. "The delay could have been an hour but it wasn't because those officers took it on their initiative. They're all dirty and they all got soaked to the bone."

The largest tree, about four feet in diameter, had stood where one of Kendro's Police Academy classmates, Randal N. Young, was killed by a drunken driver in 1991 as Young was ticketing another driver.

"I've always called it Randy's tree," Kendro said. "I think he was right there helping them push it off the road."

132 CALLS IN 4 HOURS

At 4 a.m., the storm hit.

Normally, Honolulu fire officials receive an average of 125 dispatch calls every 24 hours. But just between 4 and 8 a.m. yesterday, fire dispatchers received 132 weather-related calls, including 67 for flooding, said Honolulu Fire Capt. Terry Seelig. Between 8 a.m. and noon, the number of weather-related calls dropped to 84, including 42 for flooding.

For the next two hours, the number of calls fell to 18, including 12 that were weather related.

"It was all across the island," Seelig said. "No particular place was worse than another. It started on the west side, then Central and then Windward and for awhile it was all at one time."

Water from Lake Wilson reached the 80-foot level yesterday morning and entered the spillway, triggering an evacuation of Otake Camp, which sits downstream.

Alarms went off when the water level reached 82 feet, then rose to 83 feet between 10 a.m. and 10:30 a.m. before receding as the skies briefly cleared.

The rain also overwhelmed parts of the city's sewer system.

The Wahiawa Wastewater Treatment Plant began getting overrun at 5:23 a.m., which eventually unleashed 226,000 gallons of treated and untreated waste into Wahiawa Reservoir, city officials said.

Another 10,000 gallons of sewage overflowed from a drain line at the Sand Island Wastewater Treatment Plant. About 5,000 gallons dissipated into the plant grounds and the rest entered a storm drain that leads to Honolulu Harbor.

Another 40,000 gallons of untreated sewage spilled out of Marine Corps Base Hawai'i's sewage treatment facility and into the Mokapu Central Drainage Channel. About 2,000 gallons of untreated sewage spilled into Kane'ohe Bay near Hale Koa Beach, according to the Marines.

Staff writers Dave Dondoneau, Eloise Aguiar and Diana Leone contributed to this report. Reach David Waite at dwaite@honoluluadvertiser.com or 525-7412.