You went to a different “U.A.” Out of state, with different pro hero’s and students!. One day you and your friends went on a school trip (it was most likely a pro hero taking the class your in on a patrol mission). While you and your class were on that trip the main “U.A” (the one from the anime) also decided to take a trip to the same spot and “1-A” saw you and your class from afar

Deku: “Is that…Who are they?”

Tsuyu: “We should leave them alone Ribbit.”