Call social services and report the children not being supervised and seem to be neglected.
Call the police when you seem destroying property, either yours or other such as cars. Install discreet survaillence cameras, once that don't actually look like cameras, or out of reach of children around that side of your property. Catch the little heathens in the act. Show the authorities to get a police report.
Report to the cable companies that their equipment is being constantly destroyed by vandals. It may not lead to anything but at least you have it on record.
By pass the property manager and get the name and address of property owner. Your town may require that the owners register with city hall since they do no live on site.
Send registered letter to property manager/owner about the incidents along with copies of any police reports. If you have a lawyer friend that is willing to do you a favor, have him/her write it for you preferably on letterhead from their law firm to add impact to how serious you are to it.
Take footage and reports and sue in small claims court. Investigate to see if you can hold the property manager/owner liable for the tenants actions.