Thousands of students have marched through the streets of Chile's capital to protest recent corruption scandals and to complain about delays in a promised education overhaul.

Police said about 20,000 people took part, though student organizers estimated the crowd at about 150,000.

While it was largely peaceful, violence broke out at the end when hooded protesters threw rocks and gasoline bombs at police.

Past student marches focused on pressuring President Michelle Bachelet to fulfill her campaign promise of education reform. Students now say they're fed up waiting for changes and are disgusted by a series of corruption scandals.

They include a controversy over a bank loan involving Bachelet's son and a campaign financing scandal involving right-wing politicians and a prominent financial company.