Three Seattle police officers were injured during clashes with protesters at the annual May Day march.
Protesters, many donning black clothes and masks, threw rocks and burning objects, hurled wrenches and tossed an explosive device, according to the Seattle Police Department.
All three officers suffered serious injuries during the incident Friday evening. One officer was treated for a dislocated shoulder, another sustained a broken wrist and the third officer was left with burns to their leg and ankle.
“Seattle celebrates free speech, the right to assemble … [But] what erupted tonight is a very different story,” Seattle Mayor Ed Murray said in a statement.
“Tonight we saw assaults on police officers and senseless property damage, which cannot be tolerated. Those who are violent will be arrested.”
Officers arrested 16 protesters on suspicion of assault, obstruction and failure to disperse.
Seattle Central College, which canceled all activities for the day because of the protests, reported fires being set on the campus.
Police recovered evidence and are determining what charges the suspects will face.