The answer is: Romeo and Juliet’s tragic deaths.
In Act 1 Scene 1 from Shakespeare's "Romeo and Juliet," Prince Escalus makes reference to the Capulets and Montagues who are having a brawl in the streets of Verona. In that respect, he warns both families to stop the fight and threats them with punishent or torture. As a consequence, the event is an omen of the downfall of young Romeo and Juliet.