Demonstrations in Chile against inequality have turned violent as vandals burned two churches, virtually destroying one of them.
A police headquarters was also firebombed and shops were looted in the protests, which started peacefully.
The protests were marking a year since the start of a mass protest movement that rocked Chile for two months.
Demonstrators also urged people to vote in favour of a new constitution in a referendum next weekend.
Protesters have taken issue with Chile's constitution, which dates back to the years of military rule after Gen Augusto Pinochet seized power in 1973.
Police said 18 officers were injured on Sunday, while Interior Minister Victor Perez called on people to make themselves heard in the referendum.
"Those who carry out these acts of violence do not want Chileans to solve our problems through democratic means," Mr Perez said, vowing to punish those who committed crimes.
Masked protesters attacked churches in the capital, Santiago, setting a spire alight at one.
Police fired tear gas and water cannons during clashes.
Protests first erupted in Chile in October last year and were held almost daily, but largely subsided as coronavirus spread.
The protests were originally triggered by a rise in the price of metro tickets in Santiago, but soon became a much wider movement denouncing inequality in Chile, the high costs of healthcare and poor funding of education.
Excessive use of force by police, with hundreds of protesters blinded by rubber bullets, further stoked Chileans' anger.
At the height of the protests last October, Chile pulled out of hosting two major international summits, the COP25 climate summit and the Apec trade forum, for fear of violence.
More than 30 people lost their lives and thousands were injured during the demonstrations.