The 8.8-magnitude earthquake that struck Chile is now blamed for the deaths of at least 708 people, Chilean President Michelle Bachelet said Sunday.

Bachelet told a news conference her country faces "a catastrophe of such unthinkable magnitude that it will require a giant effort" for Chile to recover.

She spoke after a six-hour meeting with aides and emergency officials coping with the quake, which struck central Chile at 3:34 a.m. local time on Saturday.

A man holds up a Chilean flag Sunday in a flooded area after an earthquake in Pelluhue, some 322 kilometres southwest of Santiago. (Roberto Candia/Associated Press)Officials had earlier put the death toll at 300.

News of the higher death toll came as rescue crews continued to search for as many as 60 people who are feared trapped in a collapsed apartment building in Concepcion.

Crews spent the night smashing through walls of the 15-storey building to find survivors. Some of the most serious damage is in the city of 670,000 about 115 kilometres from the epicentre of Saturday's quake.

Firefighters searching for survivors in the building on Sunday were forced to temporarily halt their efforts because of tear gas and water cannons fired across the street to stop looters who were wheeling off everything from microwave ovens to canned milk at a damaged supermarket.

To quell looters, Bachelet announced that essentials on the shelves of major supermarkets would be given away under the supervision of authorities. Troops and police will also distribute food and water, she said.

The government imposed a night-time curfew in Concepcion and the Maule region to try to stop looting and soldiers were sent to the city late Sunday.

Authorities say 1.5 million Chileans have been affected by the tremor and 500,000 homes were left severely damaged. The full extent of the damage remained unclear.

Ninety aftershocks of magnitude 5 or greater have rattled Chile since the initial quake, prompting thousands of people to sleep outside their homes in tents. One aftershock was nearly as powerful as Haiti's devastating Jan. 12 earthquake.

Around Concepcion, whole villages have been flattened, highways have been sliced in two and bridges have collapsed. The city's university was among the buildings that caught fire.

In the capital, Santiago, several areas remained without power or running water. Many of Santiago's newer buildings escaped serious damage, but television pictures from the south tell a different story.

Eleanor Wachtel, host of CBC Radio's Writers and Company, went to Santiago to interview authors for her show and arrived just before the earthquake struck.

She was on the ninth floor of a hotel when the tremor shook the building for about a minute and a half. The first sign of damage she saw was a large crack in the ceiling of the lobby.

"There was a loss of power, almost immediately," she said. "People were pouring out onto the streets."

Chileans near the epicentre were thrown from their beds by the force of the quake, which was felt as far away as Sao Paulo in Brazil — 2,900 kilometres to the east.

A tsunami caused by the quake that swept across the Pacific was blamed in the deaths of at least four people on Chile's Juan Fernandez Islands. The rush of water also caused serious damage to the port town of Talcahuano. However, the tsunami caused little damage in other countries.

Officials were able to accurately predict the timing of when the first waves would arrive and as a precaution advised hundreds of thousands of people to move to higher ground.

The tsunami warning was lifted a day after the earthquake.

With files from The Associated Press