Association president Maria Gisela Rosado says the walkout began Wednesday afternoon to press the organization's demand to meet with University of Puerto Rico officials to end the clashes.
Students painting slogans on a university street scuffled with police Wednesday. Some students threw rocks at officers, who in turn swung their batons and arrested at least eight people.
Students have organized small strikes to demand the university eliminate an $800 yearly fee imposed to help reduce the system's budget deficit. Students already paid $49 per credit.