Spanish police say 25 young people were arrested in clashes between riot police and students protesting cuts in education spending in the eastern city of Valencia.
Police say six of the people detained Monday evening were minors, who have since been released, and 13 people were injured, 11 of them police.
They say students had been demonstrating peacefully for days outside a high school but officers moved in when demonstrators blocked a major thoroughfare.
Video posted on Spanish newspapers showed police treating protesters roughly, in one case slamming two young women against a car.
Valencia is one of Spain's most heavily indebted semiautonomous regions.
News reports said another student rally is planned for Tuesday.