A strong earthquake measuring 6.6 on the Richter scale struck off the west coast of Hawaii Island early Sunday morning, cutting power supply for many people on the island and causing damage to buildings.
Hawaii Gov. Linda Lingle issued a disaster declaration for the entire state about four hours after the strong quake at 7:07 a.m. (1:07 p.m. ET) Sunday.
There have been as many as 20 aftershocks, with the strongest recorded at 5.8, officials told CNN.
Emergency room ceilings collapsed and electricity went out at Kona Community Hospital on the Big Island, which began transporting seriously ill patients and nursing home patients to Hilo Medical Center around 11 a.m. (5 p.m. ET), said spokeswoman Terry Lewis.
Power was restored to Hilo on the Big Island. Power is slowly coming back on throughout Maui, the Hawaii National Guard told the Associated Press.
Officials did not have a firm estimate of how many people were without power. In areas such as Waikiki -- on the island of Oahu -- which relies heavily on tourism, visitors began lining up outside convenience stores to buy water and other supplies. Managers were letting tourists into the darkened stores one at a time.
Airports across the islands switched to emergency backup systems, which allowed inbound flights to land and a few outbound planes to depart. By midday, all flights out of the airports on Honolulu and Maui were canceled, as were flights to Hawaii from the United States mainland. At the airports still in operation, security officials checked luggage manually and agriculture agents used dogs to sniff packages and luggage because X-ray machines were without power.
Officials asked cruise ships to keep guests on board, and ships scheduled to make landfall in Hawaii were asked to head to their next location, the New York Times says.
Stuart Koyanagi, a geophysicist at the tsunami warning center, said the 6.6 magnitude earthquake was followed seven minutes later by a 5.8 magnitude temblor and by several smaller quakes. Seismologists warned of aftershocks through Monday.
Michael Poland, a geophysicist with the U.S. Geological Survey's Hawaiian Volcano Observatory, said the earthquake was likely the largest to hit Hawaii since 1989, and possibly the largest since an even bigger one measuring 7.2 hit in 1975, Reuters reports.
Prepared by Alexander Timoshik