Is the Apartment complex liable for those damages?

Nope, I don't see that the apartment complex is responsible. It may have been somebody you know from outside the complex who just doesn't like you. The apartment complex is not liable for that.

Your rights and landlord's duties as well as what how to enforce such rights or deal with a breach of duties, will all be governed by the terms of your lease which we assume is in writing. But generally speaking, the landlord does have some liability in maintaining the property as well as safety in the common areas (such as the parking lot), BUT there is often language that absolves them of any acts by 3rd parties. You should consult an attorney to have the lease reviewed and then to contact the landlord as necessary. In the meantime, you should communicate with the landlord in writing to document your complaints