The peacekeepers were, I believe, working with the protest organizers. They have people in bright vests keeping people in the right designated areas, attending to emergencies, or giving armed response when shit goes down.
You have no idea how psyched I am that they are armed. Well, not happy that this is where we've ended up, but about the fact that they're out there ready to defend the people. This isn't the first video I've seen about them jumping into action with this sort of "armed maniac" situation.