Police fired pepper spray and arrested a half-dozen people Thursday night as anti-capitalist marchers meandered through Seattle several hours after hundreds of peaceful demonstrators took part in a May Day march in support of immigrant rights and a boost in the minimum wage.

Police say they used pepper spray after some marchers threw bottles at officers in downtown Seattle.

Protesters later started trash can fires in the Capitol Hill neighborhood. Another arrest came after a brick was hurled at officers. Police say a gun was recovered from one of those arrested.

Seattle police were out in force on bicycles, foot and horseback.

Violence has plagued May Day in Seattle during the past two years, with protesters challenging police in the streets and sometimes stealing the thunder of much larger daytime events.

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