So tell me more about this "concert" (a dj spinning mp3s no doubt). Where exactly was it being held? Neighbor's driveway? Outside of the private community? Did it require any permits (there is a report that the DJ was inviting people on twitter to join for only $15).
I believe the party was being held at the HOA's community pool and clubhouse. Residents of the community were allowed to bring up to two outside guests if they liked, but it was mainly for members of the community.
The party crashers were trespassing and causing a disturbance.