What was the cause of the Boston massacre

A small argument between British Private Hugh White and a few colonists began. The argument then began to escalate as more and more colonists began to gather. They began to harass Private White by throwing sticks and snowballs at him. The crowd became more and more aggravated and eventually an object hit a soldier, causing him to fall and shoot into the crowd. After a few seconds, the remaining soldiers began firing into the crowd, instantly killing 3 colonists and having 2 die from injuries later on.