Seattle police said late Sunday that five officers were injured after anti-capitalist protesters pelted them with rocks, flares, bricks and Molotov cocktails after a May Day gathering in the city turned violent.

Nine people were arrested and authorities used pepper spray to disperse the crowd. The department said one of the injured officers was treated for a head laceration after being hit by a rock; a second was injured, but not burned after being hit by a Molotov cocktail; and a third was bitten, though it was not immediately clear by whom. Details on the other two officers' injuries weren't immediately available.

Q13Fox reported that the demonstrators also broke windows and spray painted buildings and parked cars along downtown streets.

"This is no longer a peaceful march," Steve Wilske, Seattle Police assistant chief, said in a statement on Twitter and police ordered protesters to disperse.

The clashes had been preceded by a peaceful march by advocates for workers and immigrants, just one of several events in cities nationwide Sunday to call for better wages for workers, an end to deportations and support for an Obama administration plan to give work permits to immigrants in the country illegally whose children are American citizens.

However, after the march ended, dozens of black-clad protesters gathered in a downtown park before marching through the streets. They did not have a permit from city officials, according to Q13Fox.

The station reported that several of the demonstrators carried signs, including one that said "We Are Ungovernable."

Bicycle police in riot gear pushed the protesters south past the city's sports stadiums to a Costco parking lot. Police said they then allowed small groups to disperse.

Seattle traditionally sees large, disruptive May Day gatherings. Last year police arrested 16 people during demonstrations and in 2014 10 people were arrested.

In 2013, police arrested 18 people from a crowd that pelted them with rocks and bottles.

The Associated Press contributed to this report.

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