Noise Violation Ticket

On New Years Eve 2010, I allowed my teenage daughter to have a get together at our house. No alcohol, no drugs. Was suppose to be just some of her closest friends. As the night progressed, more and more people started showing up. Hence a fight broke out in the street, with some boys that were not invited. I am the type of person who does not like violence at all, so I asked the boys to leave. While I was asking everyone to leave or go back inside the house, the cops showed up. Evidentally someone called. When the police came, I was outside waiting for some of the parents to come, and the police officer asked me what had happened. So I told him. While talking to him, another police officer went in the house and did a walk through. Found no drugs no alcohol. The cop stated that we were not in violation of anything, because the music was not loud, but if he had to come back out for any reason he would be arresting people. I told the police that the party was being shut down, and that there should be no more problems. After some of the parents came to pick up the kids, I went back inside to get my coat, for it was freezing. I instructed the remainder of the kids in the house that they could not go back outside until their parents came, and that they were not allowed to let anybody in. Next thing I know I heard a loud bang and the kids started screaming. The boy who started the first fight came back with a entourage of his friends and started attacking some of the other kids, and took it back out in the streets. This time the young man had a gun. I asked my neighbor to call the cops, but before we could make the call the police pulled up. The young man with the gun took off running. My daughter told the police what had happened and he told her that he did not care, because it was obvious that he was the victim. Instead of going after the kids who I had asked to leave, the police officer gave me a ticket for noise. I had went to admin court and spoke with the city attorney, and she said that the fine would be a minimum of $500.00 for first time violators. or I could plead not guilty and take it to court. I explained to her what happened and she scheduled it for a later court date. However, according to her, the officer who wrote the citation stated that when he arrived there were well over 400 people at my house, mind you I live in a duplex and with the garage it is only 1500 sq ft. I am not sure how 400 teenagers can fit in a living room with a couch, two chairs, a wall entertainment center, a coffee table, as well as a dining table. I explained to her that there were more than 1 police officer at the scene, and that this cop was not being honest. She told me she would have to pull out the recording and view it, so set it for a different date. My question is this, even though I had taken the corrective measures to ensure nothing else would happen, and even though I did not allow these young men back in my house, why did the law issue me a noise violation. I explained everything to him, he even heard me tell the kids that were there to get back in the house until their parents came. They did not shut the party down, I did. But because these boys came back for revenge on some other people, who by the way were gone already, because I asked them to leave to, I am being fined. I am not a irresponsible parent, and I did have my daughter ask the neighbors before she had the get togethers permission. I just feel that a crime was committed but it was not by me. Am I wrong for thinking like this? Please be honest. Thank you so much for your time in advance.