Chilean President Michelle Bachelet says the 8.8-magnitude earthquake that shattered the central part of the country and displaced some 2 million people is an emergency "unparalleled in the history of Chile."
Security forces said Monday they have arrested dozens of people for violating curfew and looting around the southern city of Concepcion and Maule regions.
President Bachelet sent 10,000 soldiers to the earthquake region to restore order, and she announced an agreement with supermarket chains to distribute food free-of-charge.
Ms. Bachelet also promised deliveries of food, water and shelter for the thousands of people living on the streets.
The president was reluctant to ask for international aid when the quake first hit, but appealed for assistance as the death toll rose to more than 700. Officials expect the number to rise as rescue workers continue to tear through the rubble.
Rescuers are still trying to reach people trapped in a toppled apartment building in Concepcion, the country's second-largest city. Searchers believe as many as 50 people may be trapped alive in the building.
Looters ransacked stores in Concepcion Sunday, stealing food and electrical appliances. Police used tear gas and water cannons to disperse a crowd of looters at one supermarket.
Saturday's early morning quake toppled buildings, overturned cars, damaged roads and bridges and brought down utility lines.
A tsunami triggered by the quake devastated some Chilean coastal towns and Robinson Crusoe Island, where the wave surged almost three kilometers into the town of San Juan Bautista.
The surge of water raced across the Pacific Ocean, prompting warnings and evacuations from Hawaii to Japan, but did little damage.
Argentina and other parts of South America also felt the earthquake.
The U.S. Geological Survey says an earthquake with a magnitude of 8 or more is classified as a "great" earthquake that can cause tremendous damage.
Some information for this report was provided by AFP, AP and Reuters.