Had this happen to the gf's z28. All 4 tires slashed, we know who did it, but can't do anything about it because we can't prove it. Police report did nothing but put it on paper. Car insurance covered it, but with a $500 deductible, it only left a few hundred for insurance to cover. File the police report, call your insurance, wait for them to take care of it, and try to relax and not kill anyone in the mean time.