Rescuers searched for survivors Monday as crews sought to deliver food and water and prevent looting after the fifth strongest earthquake in 100 years ravaged central and southern Chile.

More than 1.5 million people were without power in and around the capital of Santiago, according to Chile's National Emergency Office, but the hardest-hit areas were farther south, in the Maule and Bio Bio regions along the coast.

Authorities said 541 of the 708 reported deaths happened in Maule, where a sewer system collapsed, water towers were close to toppling and communities lacked basic services, the emergency office said.

Many people were without safe drinking water and electricity or gas service in Bio Bio, where 64 deaths occurred, according to the latest figures from the Chilean government.

Rescuers from Santiago, fresh from a stint in earthquake-ravaged Haiti, worked through the night to free people who could be trapped in a 15-story building in the hard-hit city of Concepcion in central coastal Chile, about 70 miles (115 kilometers) from the earthquake's epicenter.

Firefighters said they believed they heard tapping from inside the building. Authorities said 40 or 50 people could be inside but do not know whether they are alive or dead.

The rescue and recovery work unfolded as Chile's defense minister blamed its navy for not issuing a tsunami warning after the 8.8-magnitude earthquake rocked the South American country Saturday.

Such a forewarning could have allowed villagers on the coast to flee to higher ground.

"The truth even if it hurts [is that] a division of the Navy made a mistake," Defense Minister Francisco Vidal said.

After the quake initially struck, President Michelle Bachelet said a tsunami was unlikely.

Yet a large wave crashed later into the Chilean islands of Juan Fernandez, killing at least eight people and leaving another eight missing, the Chilean emergency office said. Waves caused damage along the coast of the Chilean mainland as well.

Dozens of countries posted tsunami warnings, and Chilean authorities later realized the earthquake generated large waves that slammed coastal areas.

"What we saw between the sixth and the ninth region is a tsunami," Vidal said.

The Navy has an emergency system under which captains in each port may issue warnings when sea levels begin to rise.

Those port captains were the ones who eventually sounded the alarm, warning residents to flee, and helped prevent additional loss of lives.

"There was a mistake," Vidal said. "Fortunately, the system was activated."

All 300 American and Chilean employees of the U.S. Embassy have been accounted for and are safe, Paul Simons, U.S. ambassador to Chile, told CNN's "American Morning."

As of Monday morning, there were no reports of any American fatalities or serious injuries, Simons said, but efforts to locate and contact thousands of Americans continue, and reports were sketchy from areas most affected by the quake.

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Calling the quake an "unthinkable disaster," Bachelet said a "state of catastrophe" in the worst-hit regions would continue, allowing for the restoration of order and speedy distribution of aid.

The government hopes to resume normal commercial air service soon, Bachelet said in remarks on the Chilean government's Web site.

Authorities also are working to prevent the possible spread of disease, she said. "Earthquakes or tsunamis like those that we have had cause a great quantity of diseases," Bachelet said.

"We're facing an emergency without parallel in the history of Chile. The passage of time has demonstrated that we're facing a catastrophe of unforeseen intensity, one that caused damages that are going to require immense, united efforts from all sectors of the country -- private and public," Bachelet said.

Looting broke out in parts of the country, including in hard-hit Concepcion in central coastal Chile, about 70 miles (115 kilometers) from the earthquake's epicenter.

Desperate residents scrounged for water and supplies inside empty and damaged supermarkets. Authorities used tear gas and water cannons to disperse looters in some areas.

The earthquake is tied for the fifth strongest since 1900, according to the U.S. Geological Survey. Another 8.8 quake struck off Ecuador in 1906.

Stronger earthquakes occurred in Russia's Kamchatka(magnitude 9), off northern Sumatra in 2004 (magnitude 9.1), at Prince William Sound, Alaska, in 1964 (magnitude 9.4) and south of Concepcion -- not far from the epicenter of Saturday's quake -- in 1960 (magnitude 9.5).

Chilean President-elect Sebastian Pi

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