My first experience with the police was just as bad. A friend and I were waiting on the porch of another friend (all like 14 years old). We were waiting for him to come home. He knew we were there waiting for him.
His neighbors yelled something to us out of their window. We went to see what they wanted, but they didn't say anything when we got near.
We went back to the porch and waited for maybe 10-15 minutes, but decided to leave as we felt really weird about those neighbors. As we started walking, a police officer pulled up screaming at us, telling us we were under arrest for throwing rocks at the windows of those neighbors. The police officer took us to the police station, put handcuffs on us, as well as shackled our feet to the floor, where we remained for like 2 hours. He made us write a statement, and then told our parents to come get us.
It was truly the most confusing thing I ever experienced. Angers me a bit today thinking about it.