Immigration protesters had taken to unlawfully blocking traffic. Officers tried to reason with them to clear the road, but some wouldn’t move. It appears that some of the protesters started to push the officers, and that’s when officers appear to have busted out the OC spray.
In the video you can see the protesters’ wails of agony. Normally, I’d feel sorry for anybody who gets sprayed, but anybody who illegally blocks traffic and then assaults officers is just bringing it on themselves.
You can see the video here: