Honolulu, Hawaii (CNN) — Residents scrambled to stock up on water and food Saturday as sirens blared across the islands ahead of a predicted tsunami, hours after an 8.8-magnitude earthquake struck Chile.

The sirens sounded at 6 a.m. local time (11 a.m. ET) to warn of a tsunami triggered by the earthquake, which killed at least 147 people.

Roads to beaches and other low-lying areas were closed and hotels were evacuating vacationers.

At Honolulu’s Hilton Waikolua Hotel, guests with cars were heading to higher ground and buses were moving hundreds to an evacuation center set up near the hotel.

At nearby supermarkets, residents stocked up on essentials like water and toilet paper in anticipation of the high waters. One sign at a local store limited families to two cases of spam.

The first wave of the tsunami was expected to hit Hilo on Hawaii’s Big Island at 11:05 a.m. (4:05 p.m. ET). There were some reports of receding water shortly after the expected landfall time had passed.

Beaches that would normally be crowded with sunbathers at midday on a Saturday were deserted. Ships and boats littered the coastline a mile offshore as commercial and recreational vessels sought safe waters.

The siren systems in each county were sounding every hour to “to alert residents and visitors to evacuate coastal areas,” Hawaii’s Civil Defense Division said in a statement.

“Residents will be advised by their respective country civil defense or emergency management agencies to evacuate coastal areas.”

The Pacific Tsunami Warning Center issued a tsunami warning, the highest level of a tsunami alert, for the entire Pacific region, including countries as far away as Russia, Japan and Australia.

California and Alaska are under a tsunami advisory.

Speaking Saturday afternoon in Washington, President Obama urged people in Hawaii, Guam and American Samoa, also under a tsunami warning, to prepare for the potential tsunami.

Local coverage: KITV, KHON

“We can’t control nature, but we can and must be prepared for disaster when it strikes,” he said in a brief statement at the White House.
He told citizens along the Pacific Coast on the U.S. mainland to be prepared as well, as “there may be dangerous waves and currents throughout the day.”

The 13th Air Force, in Hawaii, also launched planes with speakers attached to them to alert people in coastal areas not near sirens.

Hawaii Gov. Linda Lingle said she has declared a state of emergency in advance. Speaking to reporters, she urged people to listen to local officials.

“I think the success that we’re going to have in addressing this emergency is really on the shoulders of the people of Hawaii,” she said.

Pacific Tsunami Warning Center Director Charles McCreery said there was no possibility that Hawaii would not see an effect from the earthquake.

“We believe it will be a threat here in Hawaii, that’s why we initiated a warning, not only for a Hawaii, but for the entire Pacific,” McCreery said.

But he added, “We’re not expecting this to be a worst-case scenario, but we are expecting … dangerous waves coming on shore, and people need to take it very seriously.”

Speaking of the evacuations, Shelly Ichishita, spokeswoman for Hawaii’s Civil Defense Division, said people in the evacuation zones — basically coastal areas — were “asked to go inland,” she said. “We do not have evacuation shelters open.”

John Cummings, Oahu Emergency Management Department spokesman, told The Honolulu Advertiser that “If you live anywhere in the evacuation zone, you have to evacuate.”

“This is a serious event. We’re going to treat this as a destructive-type tsunami.”

The state’s two U.S. senators, Daniel K. Inouye and Daniel K. Akaka, urged Hawaii residents to remain calm.

“If you live in an evacuation zone I urge you to gather your family and please leave the area,” Inouye said.

“It is important to remain calm, listen to the news, and follow the instructions being issued by state and county civil defense officials.”

Citing the Pacific Tsunami Warning Center, the senators said some areas of Hawaii could see an initial 10- to 15-foot rise and that waves could continue for at least six hours.

“We prepare for the worst and hope for the best,” Honolulu Mayor Mufi Hannemann told CNN affiliate KHON.

Earlier Saturday, people rushed to supermarkets to stock up on food, water and other supplies.

“We got lots of water, we got our batteries, we got toilet paper,” one woman told KITV, while she stood in a line with other shoppers and their carts stuffed with supplies.

Asked if she was scared, another shopper said, “Very, very. We’re from Georgia, so …”

Businesses in the area said they will be closed all day Saturday, the affiliate reported. Hilo International Airport, on the east side of the island of Hawaii, is closed due to the pending tsunami, according to Lt. Col. Charles Anthony, director of public affairs for the State of Hawaii Department of Defense.

Lingle urged people who do not need to evacuate to stay off the roads so that emergency vehicles and people leaving coastal areas could use the roadways.

“The eyes of the world are on Hawaii right now,” she said.

Federal Emergency Management Agency Administrator Craig Fugate said his agency and the Department of Homeland Security are closely monitoring the situation.

“FEMA stands ready to assist should a request for assistance be made, and does have pre-deployed assets in Hawaii, including food, water, generators and other resources. We urge all individuals to follow the direction provided by local officials.”

Four U.S. military ships will be leaving Hawaii in the next three hours, the military said. It has six other ships and a dozen submarines in port in the state.

Another ship left San Diego, California, because of high seas, the military said.

The U.S. Coast Guard said it was closing commercial ports in Hawaii to in-bound vessels. It also said that “all seaworthy vessels are encouraged to evacuate if possible. All recreational boaters are asked to take immediate safety precautions and avoid the water.”

In 1960, a tsunami triggered by an earthquake on South America’s west coast destroyed much of downtown Hilo and killed 61 people.

The earthquake had a magnitude between 8.25 and 8.5, the U.S. Geological Survey said, and the waves in Hilo Bay reached 35 feet, but only 3 to 17 feet elsewhere.

Elsewhere, several tsunami waves have come ashore along the Chilean coast after the earthquake, USGS geophysicist Victor Sardina told CNN.

He said the largest was recorded at 9 feet near the quake’s epicenter. Another wave of 7.7 feet hit the Chilean town of Talcahuano, according to Eric Lau of the Pacific Tsunami Warning Center.

Video from the town showed one car sitting in a large expanse of water.

A large wave on the island of Juan Fernandez — 400 miles (643 km) off Chile’s coast — killed three people, Provincial Governor Ivan De La Maza said. Ten people were missing.

Although the initial tsunami waves are not supposed to hit Hawaii until mid-morning, McCreery said the threat would persist for hours.

He said the first tsunami waves would sweep across Hawaii in about 30 minutes.

“And then the hazard will go on for many hours, because these waves, they get reflected off the islands, they wrap around the islands, and it becomes a very complex wave field that persists for quite a while.”

In the Philippines, state seismologists were monitoring the possibility of waves reaching the Southeast Asian country, the official news agency there reported.