The scene starts off with the Capulets Gregory (left) and Sampson (right) having a conversations and talking about what they may do if a Montague threatens them.
Then the Montague names Abram ( far right ) enters and then Sampson and Gregory notice he is there. When they notice they then automatically try to threaten one another because they dislike the Montagues.
Since Sampson and Gregory are trying to start a fight with Abram to prove who is more worthy a fight then breaks out. The two sides start to sword fight as their way of handling the over all conflict situation.