City lifeguards also reported that one person may have fallen victim to the high surf in Makaha.
Roy Matsuura, National Weather Service forecaster, said 25-foot waves were expected along the North Shore generated by a low pressure trough 800 miles north of the island chain.
Surf was running between 15 to 20 feet on the North Shore and 10 to 15 feet on the west side. North Shore beaches from Haleiwa to Kahuku were closed as was Yokohama Bay and Kaena Point State Park on the west coast of the island.
City lifeguards were advising people to stay away from the North Shore because of high surf and debris in the water from runoff, said Jim Howe, operations chief of the city's Ocean Safety and Lifeguard Services division.
Howe said lifeguards were searching for a man whose van was parked at the beach at Makaha. "We're quite concerned about that," he said.
"The van was open with no one in it, and we are trying to find its occupant," Howe said.
Oahu Civil Defense reported significant road damage to Kamehameha Highway near Chun's Reef caused by surf and flood waters.
At least three island public schools and half dozen private schools were closed because of flooding. No parts of Oahu were spared from the heavy early morning downpour that dumped nearly an inch of rain on many parts of the island during a 15 minute period.
A Kaneohe resident was temporarily trapped in a sinkhole near Aumoana Place next to the Kaneohe Yacht Club.
Landslides, power outages, traffic problems, flooded homes and roadways, stranded motorists, toppled trees, and fallen retaining walls were the order of the day because of the overnight storm.
After leaving Oahu, the line of showers also stormed into Molokai today and the national weather service issued the possibility that part of the storm front could "back pedal" and return to Oahu later this evening.
Sunset Beach Elementary, Haleiwa Elementary and Kahuku Intermediate and High schools closed their doors and electrical power was out in some North Shore areas.
A few North Shore residents gathered at Sunset Beach Elementary School last night to escape rising flood waters.
About 1,000 homes and businesses were without power between Kuilima Turtle Bay Resorts and Sunset Beach.
The storm cut electrical power at 1 a.m., but by 7:36 a.m. electricity was restored to the area. Eight hundred residents in Waikiki also were without electricity for nearly an hour this morning.
Tom Heffner, National Weather Service spokesman, said hardest hit areas were Waianae, Punaluu, Waimanalo and downtown Honolulu.
The rain was so intense in Windward Oahu that more than 3 inches of rain were recorded at Olomana for the six hour period that ended at 8 a.m.
Other Windward Oahu rain stations reported 2.79 inches at Waihee and 2.78 inches at Ahuimanu.
On the other side of the island the rain gauges at the Aloha Tower recorded 2.94 inches, while the Manoa Lyon Arboretum listed 2.84 inches during the same period. Nearly 2 inches were recorded in Palolo Valley.
On the Waianae coast, the Makaha Valley Tower complex was hit by a massive mudslide at about 2 a.m. and extensive damage was being assessed.
Heffner said a line of heavy showers and thunderstorms moved eastward over Oahu early this morning from Kauai.
Paul Takamiya, Oahu Civil Defense spokesman, said there was major flooding along Kamehameha Highway between Kahuku and Haleiwa, closing the road because of the erosion caused by the rain and wave action.
Farrington Highway along the Waianae Coast was barricaded in some spots because of water. Also closed were parts of Lagoon Drive and Nimitz Highway.
A Red Cross and civil defense shelter was erected at Waianae District Park and more than 20 residents sought help.
In downtown Honolulu, businesses along King, Alakea and Merchant streets sought aid to keep the high water from entering their stores.
Residents who hadn't left their homes and motorists stranded on the roadways besieged 911 lines. A landslide was reported at Auwaiolimu St., mauka of Hookui in Papakolea. The mountain is coming down, a caller reported.
Residents off Lehua Road in Pearl City, makai of Kamehameha Highway reported homes flooded.