Call the PD, ask for the person who was watch commander last night, and then lay into him about how inappropriately the guy acted. When I was a kid I got into a similar situation...I was in an industrial park in the middle of the morning on a saturday with 2 friends walking around. I walked out from behind a stack of pallets right into the barrel of a cop's gun. Now...seeing as how I was about 12 at the time I figured he would've lowered his gun. Nope. He kept screaming at me asking me why I had my hands inside my shirt.
After the third command to remove my hands I just gave him the finger. They (there were 2 cars...apparently all cases involving preteens requires backup) actually frisked all 3 of us and kept asking why we had knives...Swiss Army knives, mind you. Then they drove us out of the industrail park, the opposite direction of the way we needed to go to get back home, and told us to get out start walking. All in all I don't mind cops, but man I'd love to run into one of those officers today.