Question on cap gun legality?

So a little quick back story. Me and some friends made some water balloons and were going to get another friend to come outside and yada yada. While we were waiting in the street at night. We noticed the neighbor across the street noticed we were out there. Me being the nervous wreck I always am were scared he was going to call the cops or something. Anyways the friend came out suspicious and we tried to lure him over yada yada. Long story short we started throwing them and the neighbor started firing what im guessing was a cap gun at us. Now, from a legal standpoint what we did breaks some laws. But is him firing at us break anything?