An Associated Press photographer witnessed people dragging church pews, statues of Jesus and other religious iconography from La Asuncion church onto the street and setting them on fire. Ashes spread to Santiago's Plaza Italia square where thousands were chanting and holding banners, while others turned on the lights on their cellphones and waved Chilean national flags.
Smoke also billowed from the nearby headquarters of Pedro de Valdivia University, though it wasn't known if protesters started the fire. Authorities said they were still investigating the cause.
Most of the protests over the past 22 days have been peaceful, but some have turned violent. Some rock-throwing demonstrators have been clashing with riot police, who respond with tear gas and water cannons.
The unrest began last month over a subway fare hike with students jumping turnstiles in protest. Demonstrations then erupted into clashes, looting and arson and the movement spread nationwide with a broad range of demands, including improvements in education, health care and a widely criticized pension system in one of Latin America's richest, but most socially unequal countries.
"We still haven't achieved anything, so we're going to keep protesting," said 17-year-old student Ginette Pérez, who joined the crowds flooding the streets Friday.
At least 20 people have died and an estimated 2,500 have been injured in the protests, which also forced the cancellation of two major international summits in Santiago.
Associated Press writer Patricia Luna contributed to this report.
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