My brother had some friends that thought it would be smart to make a little river of softener salt in our front yard, and ketchup and mustard on the driveway. When we found out who it was, they did email the parents. One mom wrote back and insisted she was home and the kids didn't leave. Not until my dad talked to one of the kids on the phone, who he had previously coached in basketball, and said, "if you don't want to be honest I'll call the police," did the truth come out. That mother has always been kind of a piece of work, though.
Parents insisted each of their kids owed an apology and help with anything needed to clean it up.
Do you know the parents? Is it something the kids had against lil or was it done to try and be funny? If you know the parents, and believe they'll understand and do what's right, I'd let them no.
Once again, congrats on tonight