My car was damaged by the School car Park that does not have any secure bolt can I hold the school lia?

While driving into the school carpark where i work my car was damaged by the gate which flung into my car because it did not have any bolt to secure it. This damage is costing me quite a lot. To put it through my insurance it will cost me $500 in access payment. Can I hold the school liable for the damage and how can I go about it.