You arrive with two other units, park your cars away from the party, and start to walk down. How the crowd responds will determine your next step. You confirm that aviation is almost there and ask them to fly over and briefly hit the house with some light and remain in orbit. As you make your way down the street, a few members of the crowd start shouting obscenities and ugly remarks. You can see that many people are moving toward the front of the house as if to block your way in.
You back off and call for the rest of your officers. You have one unit drive up with lights and have the officers follow behind the car. They run up, form a wide horseshoe-shaped perimeter, and hold. You have K-9s visible at each end. Over the PA, you call for the owner of the house to step outside by name. Meanwhile, people are still leaving and you let them.
After a few minutes, the crowd starts to calm down as their numbers and nerve starts to dissipate. Your reasonable show of force is working. The owner comes out of the house and meets you across the street. He apologizes and tells you it's just a going away party for his son who is leaving for the military. He had no idea it would get this big and no one was paying any attention to him. You ask about fights and weapons and he states there have been none.
By the end of your conversation, the party has all but stopped except for family, close friends, and a handful of onlookers. The number of parked cars is manageable. There really isn't any further action needed.
The owner appreciates the way you handled the call. You thank him, wish his son well, and leave the area as professionally as you came in. The remaining friends decide to take the new recruit to a sports bar and continue their party there.