Chile's president appealed on Tuesday for calm in the earthquake-ravaged city of Concepcion, vowing a stern response to any renewal of looting and violence. Michelle Bachelet said 14,000 troops are now in the region, after dozens of looters were arrested.
As night fell curfews were imposed across four major urban centres in Chile, including an 18-hour curfew in one if its largest cities, Concepcion. Some half a million people are homeless in a city now under military control.
The death toll from the 8.8-magnitude quake now stands at almost 800, officials say, but emergency workers also say 19 people are still unaccounted for.
One mayor, from Hualpen, near Concepcion, said many on the streets were more terrified of crime than aftershocks.
The thugs have taken over the city. Now we are not afraid of the earthquakes, we're afraid of the criminals, Marcelo Rivera told a Chilean radio station.
Armoured vehicles have been positioned at stationed at strategic points across Concepcion and armed soldiers patrol the streets.
Groups of residents are reported to have gathered together to form vigilante groups to confront would-be looters.
A special air route is being set up to deliver aid from the capital, Santiago, to Concepcion, 430km away.
But security in the city remains a key concern after shops and homes were looted on Monday and police made a large number of arrests.
The deteriorating security situation in Concepcion comes despite the influx of thousands of troops to reinforce local police.
We can say that, according what we've been told from the area, the situation in Concepcion is under control today, President Michelle Bachelet said on Tuesday. But, she added, authorities would take any necessary measure to stop renewed looting.
Our principle objective is to go and help people tackle the emergency in the disaster zone.
I want them [looters] to understand this and that they'll receive rigorous legal action. We will not tolerate such actions.”
Many of the city's 500,000 inhabitants are short of food and have seen their water and electricity supplies cut off.
Some residents quoted by Reuters news agency said they were organising groups to defend their property.
The government admits that its attempts to provide aid swiftly have been hampered by damaged roads and power cuts.
The air supply route between Santiago and Concepcion will help the authorities send more than 300 tonnes of aid, including 120 tonnes of food, to the worst-affected area of the country.
International aid has begun arriving. Neighbouring Argentina is flying a field hospital over the Andes to Chile and has pledged half a million litres of much-needed drinking water.
Brazilian President Lula da Silva flew to Santiago and offered his nation's support, as did US Secretary of State Hillary Clinton and Peruvian president Alan Garcia.