Violence erupted on the streets of Chile's capital Tuesday as tens of thousands of students staged another protest to demand education reform.

Riot police used tear gas and water cannon in Santiago as masked demonstrators hurled objects at them and set vehicles on fire. Police estimated that at least 60,000 people massed in the streets for the latest protest. Last week, another demonstration led to the arrests of at least 800 people.

Many students have complained about prohibitively expensive education and difficult university entrance requirements. They also say the education system is not funded properly.

President Sebastian Pinera announced cuts in the education budget earlier this year. The president has called on students to reach a negotiated solution with the government based on 21 proposals he presented, but no agreement has been finalized.

The Chilean leader also faces sagging approval ratings, which now have fallen to about 26 percent.