Chile was under curfew for the third night in a row on Monday as violent protests and looting that have left 12 people dead raged on into the working week.

Protests originally against a hike in metro fares have turned into anger at the military and Chilean President Sebastian Pinera, who on Monday night proposed a “social agreement” to meet the demands of demonstrators.

Army general Javier Iturriaga, charged with security in the capital, said the 11pm GMT to 9am GMT curfew was “necessary” as Santiago and several other cities were once again gripped by violence.

But in several parts of the capital, protesters defiantly ignored the order and faced off with security forces.

Earlier, a young man died after being hit by a military truck during the looting of a fishing company in the southern city of Talcahuano, the prosecutor’s office said on Monday.

Pinera said on Sunday the country was “at war” as five people died when a factory in a Santiago suburb was torched by protesters, and two women also died after a supermarket was set ablaze by looters.

Since Chile’s worst outbreak of social unrest in decades began on Friday, almost 1,500 people have been detained.

Once again on Monday, security forces – some 9,500 of which have been deployed – used tear gas and water cannon on the most unruly demonstrators.

Thousands of protesters gathered peacefully in the main Plaza Italia square in the capital on Monday, chanting “Pinera Out!” and “Get out military!”

Art teacher Camila Rojas, 29, said protesters had many demands, but “Pinera’s resignation is the first thing”.

And while some broke up curbs to throw stones, smashed bus shelters, looted shops, set up barricades and started fires, the vast majority in the capital were in a festive mood, chanting, banging drums, playing music and dancing.

“We have to have a party to cancel out in a way those who are doing the excesses,” Marcelo Gonzalez, 25, an engineering student with a drum said.

A fuming Pinera said on Sunday: “We are at war against a powerful, implacable enemy, who does not respect anything or anyone and is willing to use violence and crime without any limits.”

Santiago and nine more of Chile’s 16 regions were under a state of emergency, Pinera confirmed late on Sunday, with troops deployed on the streets for the first time since Augusto Pinochet’s military dictatorship from 1973 to 1990.

But the president was in a more conciliatory mood on Monday.

He announced a meeting the following day with rival parties to work on “a social agreement that will allow us all together to rapidly, efficiently and responsibly approach better solutions to the problems afflicting Chileans”.

While the metro fare hike – which would have raised the price of peak hour travel from $1.11 to $1.15 – was a trigger, protesters are mostly angry at social inequality.

Long lines formed at shops, service stations and bus stops while the Santiago metro service, suspended on Friday, was partially running again on Monday as some people returned to work.

In Santiago, many employers cancelled the working day, while most schools and universities remained closed.

Hundreds of people remained stuck at Santiago’s airport as dozens of flights were cancelled or delayed.

Among the buildings torched and damaged in the unrest were the headquarters of the Enel Chile power company and a Banco Chile branch – both in the centre of Santiago – and Chile’s oldest newspaper, El Mercurio, in Valparaiso.