One man was reported shot and killed, and about 160 people were arrested as police tried to control post-earthquake looting in parts of Chile.

The 8.8-magnitude earthquake on Saturday killed at least 723 people and damaged at least 500,000 homes, Chilean officials said.

The shooting death and the arrests took place in Concepcion, the largest city near the epicentre of the quake, after an overnight curfew was imposed. Markets in the city were sacked on Sunday and there were additional reports of looting on Monday.

Meanwhile, the United Nations willl rush supplies and support to Chile to help deal with the aftermath of the quake, a UN spokeswoman says.

UN humanitarian spokeswoman Elisabeth Byrs told The Associated Press that Chile made an official request for assistance Monday, two days after the quake struck about 325 kilometres south of the capital, Santiago.

In Santiago, people started returning to work Monday, but schools were closed. Meanwhile, rescue crews in Concepcion — which is 115 kilometres from the epicentre of Saturday's quake — were still searching for survivors.

Michael Black, a Santiago aid worker with World Vision, the non-government agency, said the death toll could reach 1,000.

“We thought in the first 24 hours that we were coping with it,” Black said. “Now we’re finding out every hour that the magnitude of this is gigantic.”

He said it will be difficult for agencies to distribute aid to the roughly two million people believed to be affected. The quake damaged airports and roads, including the Pan-American Highway, Chile's main north-south thoroughfare.

Chilean officials have struggled to assess the damage caused by the massive earthquake and the more than 100 aftershocks that have rumbled through the country since Saturday.

On Sunday, President Michelle Bachelet said Chile needs field hospitals and temporary bridges, water purification plants and damage assessment experts — as well as rescuers to help relieve exhausted workers.

"We are confronting an emergency without parallel in Chile's history," Bachelet said.

Bachelet — who will be replaced by president-elect Sebastian Pinera on March 11 — gave the military control over security in the provinces of Concepcion and Maule and announced a 9 p.m. to 6 a.m. curfew for all non-emergency workers. She ordered troops to help deliver food, water and blankets, and to help clear rubble from roads.

Bachelet also ordered authorities to identify the dead quickly and return them to their families to ensure "the dignified burials that they deserve."

Thousands of people have been forced to move out of their homes into tents set up in parks and on grassy highway medians.

337 Canadians missing after quake

Foreign Affairs officials said roughly 5,000 Canadians live in Chile, with about 1,000 in the area hit by the quake.

In a statement issued Monday afternoon, Foreign Affairs said 520 missing Canadians had been located, while another 337 are unaccounted for.

In Washington, the State Department urged Americans to avoid tourist and other nonessential travel to Chile. Secretary of State Hillary Rodham Clinton planned to briefly visit Santiago on Tuesday as part of a five-nation Latin America trip.

With files from The Associated Press