threw rocks, smoke bombs and soda cans at officers during a May Day rally, while thousands more marched in other major cities.At least three people were arrested. Several businesses in Portland's downtown area were also vandalized by groups of people wearing black masks who were seen breaking storefront windows, throwing incendiary devices and attacking a police vehicle.The violence prompted authorities to cancel the permit for the march and warn that anyone remaining on the streets risked being arrested. People were advised to stay away from the area.
https://www.yahoo.com/news/riot-declared-during-us-may-day-protests-portland-020718138.html