Hundreds of students blocked streets in Lima, Peru, and hurled rocks at police, demanding the release of classmates who were arrested in campus raids last week on suspicion of being leftist guerrillas. Merchants in the area closed their shops when the protests began, and traffic was paralyzed. Police raided three campuses of San Marcos University on Friday and arrested nearly 800 people. More than 500 students and professors were later freed, but an Interior Ministry spokesman said that charges will be brought against the 273 still in custody. Campuses had been off limits to police until Friday because of the centuries-old Latin American tradition of university autonomy.