Some masked people threw down a trash container in a "day of struggle" at Vitoria-Gasteiz (they did not even set fire to it... what kind of "struggle" is that!) Police arrived at the scene and had all students at the nearby school retained for 40 minutes of school time, while they proceeded to identify them.
While some teachers protested in vain that the activists were none of their students, the directors of the center hid in their offices and let the police do.
And then they are surprised that police and hierarchies are so much hated by the Basque youth. An eye-opening experience for many of these young people I presume.
Source: La Haine.