LIMA, Peru — With frantic rescue efforts under way, a rising death toll and isolated outbreaks of looting, the Chilean president on Sunday issued an order that will send soldiers into the streets in the worst-affected areas to both keep order and speed the distribution of aid.

After huddling in a crisis meeting with her cabinet, President Michelle Bachelet called the damage caused by Saturday’s magnitude-8.8 quake “an emergency unparalleled in the history of Chile.” She said the death toll had reached 708 and suggested it would probably grow in the days ahead.

The police fired water cannons and tear gas to disperse hundreds of people who forced their way into shuttered shops in the southern city of Concepción, which was devastated. But law enforcement authorities, heeding the cries of residents that they lacked food and water, eventually settled on a system that allowed staples to be taken but not televisions and other electronic goods.

Ms. Bachelet later announced that the government had reached a deal with supermarket chains to give away food to needy residents.

Image Julia Gallegos, left, and Telia Maturana at dawn on Sunday in Talca, Chile, near the epicenter. They spent Saturday night just outside of their destroyed homes. Credit... Tomas Munita for The New York Times

Her aides also called on residents not to hoard gas or food, both of which were being bought up in huge amounts by residents fearful of shortages.

Using power saws and their bare hands, rescue workers atop the rubble of collapsed buildings tried to pull out those caught inside. Although there were successes — like Julio Beliz, who managed to free his neighbor from the rubble in Santiago after hearing him yell out, “Julio, help me!” — the search for survivors was frustratingly slow.

“It’s very slow, dangerous work, because on top of it all, it’s still shaking there,” said Victoria Viteri, a spokeswoman with the national emergency office in Santiago, referring to rescue efforts in the country’s hardest-hit areas.

The earthquake, one of the strongest in recorded history, left a devastating footprint on a country that knows quakes well.

Residents of a collapsed 15-story apartment building in Concepción, opened just months ago, were outraged that it had been so badly damaged and were convinced that contractors had not complied with building codes that require buildings to be able to withstand temblors. Already, there was talk among residents of taking builders to court once the emergency is over.

Image Officers tried to control a crowd pushing into a supermarket to buy supplies on Sunday in the southern city of Concepción. Credit... José Luis Saavedra/Reuters

In Cobquecura, 50 miles north of Concepción, state television showed collapsed bridges, crashed buses and sunken pavement. Residents had fled to the hills, prompting local journalists to declare it a virtual ghost town.

In remote coastal towns, waves had obliterated homes, and boats were found on land next to overturned cars. The authorities acknowledged that the damage was spread over such a vast area that they were just beginning to get a grasp on it.

Early Sunday, a 6.1-magnitude aftershock, one of more than 100 that have followed the original quake, sent residents scrambling again for cover. With the earth still unsettled, many Chileans have opted to camp outside.

In Maipú, outside Santiago, the capital, the authorities inspected an apartment building, found it relatively stable and allowed residents half an hour each to hustle inside and remove any personal belongings, local media reported. At another building nearby, however, the damages were considered too severe and the city told residents to stay out.

The National Office of Emergency raised the number of displaced people on Sunday to two million.

Among the quake’s victims were Lurde Margarita Arias Dias, 24, and her infant child, Peruvian immigrants who were crushed as a wall toppled in their Santiago home.