Someone watching our house?

It all started one day when my mom happened to look over and spot someone taking a picture of our house riding in a blue van. They stopped in front of our house took a picture and drove further into the neighborhood. Then they returned 2 minutes later driving out and when they saw us they dashed out. Since then we witnessed quite a few times a car stopping in front of our house till they see us in the window and driving off. Once at night. And today a completely different car was parked outside of my house. Gold cadillac. It sat in front of our house and as soon as I walked in front of our window they hauled azz. They had a black license plate with gold lettering which I didn't have time to read. If this helps any... Should I be concerned. Are the FBI watching us or crooks?? Please Offer some istance. I'm only 16 and want to be safe here.