The car belonging to the family was targeted as hundreds attended an all-day Feis being held in the Long Tower Youth club on Saturday.
Councillor Kelly said “This is a despicable act. Here we had hundreds of people attending a very positive event for the area and indeed the entire city and someone decides they are going to go out and target a few cars.
I would appeal to anyone with even the slightest piece of information in regards to those behind this to bring it forward to the police straight away. And if anyone finds someone’s discarded personal belongings in the general area to hand them in.