CONCEPCION, Chile -- Troops fired teargas and imposed a curfew Monday to stop looters running off with trolleyloads of goods from the wreckage of Chile's quake as rescuers scrabbled through rubble for survivors.

As President Michelle Bachelet said she expected the death toll of 708 to rise, the scale of the devastation wrought by Saturday's 8.8-magnitude quake was becoming clear from seaside towns and villages engulfed by giant waves.

State television reported that more than 300 bodies had been found in the swamped fishing village of Constitucion alone, leaving survivors to stare in disbelief at the seaweed clinging to what was left of their livelihoods.

The mayor of Chile's worst-hit main city of Concepcion pleaded urgently for help as rescuers with heat detectors hunted for dozens of people believed to be trapped in a 15-story apartment block toppled on its side by the quake.

The army was also called in to help the overwhelmed police force deal with looters, some of whom dragged shopping trollies full of provisions while others made off with plasma TVs and electrical appliances.

Guillermo Ramirez, military commander of the central Maule region, sent soldiers with megaphones to warn the 500,000 inhabitants of Concepcion of the dusk-to-dawn curfew they had to observe.

"I would advise criminals not to mess with the armed forces. Our response will be severe, but within the context of the law," he told would-be looters.

As they struggled to keep order, the troops fired tear-gas and water cannons on residents, driven to desperation by a lack of water and electricity.

"We need food for the population. We are without supplies, and if we don't resolve that we are going to have serious security problems during the night," said mayor Jacqueline van Rysselberghe, warning of grave "social tension."

President-elect Sebastian Pinera said the situation in Concepcion was dangerous.

"When we have a catastrophe of this magnitude, when there is no electricity and no water, the population becomes preoccupied and starts losing the sense of public order," Pinera said.

Bachelet, who is due to hand over power to Pinera on March 11, said the air force was to begin flying in food and vital aid to badly hit areas, some of which were largely cut off by the quake.

The government admitted it had erred by failing to warn Chileans about the tsunami risk following Saturday's 8.8-magnitude quake.

Official data from US experts at the Pacific Tsunami Warning Center put the biggest tsunami wave at 2.6 meters (8.5 feet). The wave came without warning for many, sweeping helpless people out to sea and reducing all but the strongest structures in its path into useless flotsam and jetsam.

The navy "made a mistake by not issuing a tsunami alert," said Defense Minister Francisco Vidal.

Some two million Chileans, or one eighth of the entire population, are estimated to have been affected by Saturday's temblor, the seventh most powerful on record.

The worst disaster to befall Chile in 50 years, sliced main highways with massive fissures and bridges and overpasses lay in crumpled heaps and at twisted angles, unpassable and going nowhere.

Officials said 1.5 million houses and buildings were destroyed or badly damaged. The historic center of the town of Curico was said to be about 90 percent destroyed by the quake.

Unlike Haiti, struck by a devastating 7.0-magnitude earthquake on January 12 which killed 217,000 people, Chile is one of Latin America's wealthiest countries and has adapted its defenses since a world record quake in 1960.

But the total value of economic damage is still likely to range between 15 billion and 30 billion dollars, or 10-15 percent of Chile's real gross domestic product, the US risk modeling firm EQECAT predicted.

Experts said the quake, which struck off the coast and caused tsunami alerts in 53 Pacific-rim countries, was caused by the subduction of the Nazca plate beneath the South American plate.

US Secretary of State Hillary Clinton, who had planned a Latin America tour before the disaster struck, will visit Santiago on Tuesday and plans to meet both Bachelet and Pinera, officials said.