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SEATTLE -- Police say black-clad May Day marchers hurled wrenches and rocks at officers and hit police with sticks as a Friday evening march through a Seattle neighborhood turned violent, injuring three officers.
Police responded with pepper spray and pepper balls, quickly arresting a half dozen people. Officers said several dozen vehicles were damaged.
Seattle police Capt. Chris Fowler declared the evening event "has turned into a riot." Mayor Ed Murray said police would continue to work to protect people and property.
Police said 15 people were arrested.
Bicycle officers shadowed the marchers, keeping them off Interstate 5 and away from downtown. They eventually wound up back at the plaza where they began what was billed as an anti-capitalist march.
Hundreds of people earlier joined in peaceful May Day marches in Seattle in support of workers' rights, an end to police brutality and other causes.
The initial Seattle march ended with a rally at the downtown federal courthouse.
We are keeping track of the latest at the scene in our LIVE BLOG below: