Police pepper sprayed University of California-Davis students during an Occupy Movement protest on campus.  The students were all seated on the ground in a non-threatening manner, yet the policeman sprayed the 30 or so students from a foot or two away.

The descpription on the YouTube page says

During peacefully Occupy Movement, police came in to tear down tents and proceeded to arrest students who stood in their way. Once students peacefully demanded the release of the arrested, a police officer unnecessarily pepper sprays the students to open a path for the rest of the officers.