Bicycle detail

I was about to head to class when I noticed my bike frame completely gone and all that was left was the secured front wheel, realizing I failed to properly lock the bike. I had always locked the front wheel to the bike rack only, which allowed the thief to unscrew the wheel from the rest of the bike so while no lock was broken, the bike was taken out, only leaving the front wheel and lock behind. I know that the bike was still here yesterday as I went outside and was able to see it still in place. I only realized it was stolen when I went to go to class.