Why did Boston colonists and British soldiers clash at the Boston massacre?

On the cold, snowy night of March 5, 1770, a mob of angry colonists gathers at the Customs House in Boston and begins tossing snowballs and rocks at the lone British soldier guarding the building. The protesters opposed the occupation of their city by British troops, who were sent to Boston in 1768 to enforce unpopular taxation measures passed by a British parliament without direct American representation.