Did I see a thief?

So I was playing outside with my little brother and then all of a sudden we saw a person with a shopping cart full of clothes. They dropped the clothes, and when they saw us they started freaking out and I pulled out my phone and then they started freaking out even more and then they sped away with the shopping cart full of clothes but left some clothes in the road. Do you think I just saw a thief or just a normal person? I think I saw a thief because people aren't supposed to remove shopping carts from stores. What do you guys think? What should I do? I have already told my dad before you guys start saying well tell your parents.
Did I see a thief?
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