'Chilling' video indeed...

"Chilling" is the one word for this, but you could add any number of similar adjectives to describe this scene. I watched this YouTube footage last night and I was appalled.

Whatever your views on the 'Occupy' protest in the US and the copycat protest camp at St.Paul's in London, the seemingly casual use of pepper spray on these students is indefensible.
http://www.independent.co.uk/news/world/americas/outcry-over-chilling-campus-pepper-spray-use-6265203.html