Photo: The Canadian Press

Traditional Aztec dancers headed up the annual El Comite May Day March for Worker and Immigrant Rights in Seattle.

At least four people have been arrested and two police officers injured in Seattle following clashes between anti-capitalist protesters and authorities on May Day.

Seattle police used pepper spray to disperse the protesters Sunday evening after authorities say rocks, flares and bricks were thrown at officers downtown. Police also said Molotov cocktails were thrown at them.

Authorities said two officers were hurt - one treated at the scene for a head laceration. Details about the other officer's injury weren't immediately available.

Dozens of people dressed in black had gathered at a downtown park following a peaceful, permitted march by advocates for workers and immigrants. They marched through downtown and were later pushed south by officers in riot gear on bikes.

The anti-capitalist demonstrators, who did not have a permit from city officials, carried signs, including one that said "We Are Ungovernable." The group gathered at the downtown park before starting to march through the streets.

Some downtown businesses had earlier boarded up storefronts, anticipating violence. Police reported seeing people with poles with bolts, rocks and cans of spray paint in the crowd. Police reported some broken windows.

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. Storefronts in downtown Seattle have also been smashed in previous protests.

Five cops injured, 9 protesters arrested during violent May Day clashes in Seattlehttps://t.co/aIX7bAo9b4

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