The latest attack on police has revived security concerns in the South American nation.
It remains unclear who carried out the assault on Chile's national police force in the Biobío region some 400 kilometres south of Santiago, the capital.
But a long-simmering conflict between the Mapuche Indigenous community and landowners and forestry companies in Biobío and Chile's Araucanía region farther south has intensified in recent years.
That has prompted the government to impose a state of emergency and deploy the military to provide security.
"There will be no impunity," Chilean President Gabriel Boric said, declaring three days of national mourning on Saturday, after firefighters dousing the burning police car made the grisly discovery.
The spate of bloodshed has tested Boric, who came to power in 2022 promising to ease tensions in the region, where armed Mapuche activists long have stolen timber and attacked forestry companies they claim invaded their ancestral lands, among other targets like churches and national institutions.
But the Indigenous community's distrust of authorities has deepened, spurring violence even as Boric's administration has touted its success in reducing Chile's national homicide rate by 6 per cent, according to government figures from 2023 published earlier this week.
"This attack goes against all the enormous strides that have been made," said Interior Minister Carolina Toha, a centre-left former mayor of Santiago appointed as minister in late 2022 to boost Boric's position as his approval ratings dipped.
Describing the assailants as "terrorists", Boric travelled south to personally offer condolences to the victims' families.
The Carabineros, Chile's national police force, said they were "working to the best of our abilities" to catch the assailants but declined to comment on possible leads.
The killing had been well planned, early reports suggest, timed to coincide with National Police Day, celebrating the 97th anniversary of the establishment of the Carabineros in Chile. It was the second such fatal attack on the force this month.
Carabineros general director Ricardo Yanez said the officers had been dispatched in response to fake distress calls from the rural road, where they were met with a barrage of gunfire.
In Chile, about one in 10 citizens identify as Mapuche, the tribe that resisted Spanish conquest centuries ago and was only defeated in the late 1800s after Chile won its independence.
Large forestry companies and farm owners control an estimated 500-700 kilometres of the land originally belonging to the Mapuche, many of whom now live in rural poverty.
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