Thousands of protesters in Peru, many from the country's heavily indigenous south, have descended on the capital Lima, angered by a mounting death toll since unrest erupted last month and calling for sweeping change.
Police estimated the march at 3500 people, but others speculated it attracted more than double that.
Rows of police in riot gear faced off against rock-hurling protesters on some streets, and one historic building in the city's historic centre caught fire late on Thursday.
The building, on San Martin Plaza, was empty when the massive blaze ignited from unknown causes, a firefighter commander told local radio.
Canada-based miner Hudbay said in a statement that protesters had entered the site of its Peru unit, damaging and burning key machinery and vehicles.
"This has not been a protest; this has been a sabotage of the rule of law," Prime Minister Alberto Otarola said on Thursday evening alongside President Dina Boluarte and other government ministers.
Interior Minister Vicente Romero disputed claims circulating on social media that the Lima blaze had been caused by a police officer's tear gas grenade.
In the past month, raucous and sometimes deadly protests have led to the worst violence Peru has seen in more than two decades, as many in poorer, rural regions vent anger at the Lima establishment over inequality and rising prices, testing the copper-rich Andean nation's democratic institutions.
Protesters are demanding the resignation of Boluarte, snap elections and a new constitution to replace the market-friendly one dating to the days of right-wing strongman Alberto Fujimori in the 1990s.
The protests have been sparked by the dramatic December 7 ouster of leftist former president Pedro Castillo after he tried to illegally shutter Congress and consolidate power.
In buses and on foot, thousands journeyed to Lima on Thursday, carrying flags and banners blasting the government and police for deadly clashes in the southern cities of Ayacucho and Juliaca.
The unrest spread far beyond the capital.
In southern Arequipa, police fired tear gas at hundreds of protesters who tried to take over the airport, leading officials to announce the suspension of operations at the Arequipa and Cusco airports.
Boluarte said the airports, as well as one in the southern city of Juliaca, had been attacked "in a concerted manner" and vandals would face "all the rigour of the law".
The mounting death toll stands at 45, according to the government ombudsman, with the latest victim on Thursday coming from southern Puno region, a woman who succumbed to injuries from a day earlier.
Another nine deaths are attributed to accidents related to protest blockades.