So, funny story... Except for me... I forgot my keys this morning, and it's slick ice at 0 degrees outside... So I called to get let into my work. I grabbed the master key at the reception desk, unlocked my door, and left it unlocked. At about 15 minutes before everyone left, I got called to another person's office to do some work. He left as soon as I finished, and I didn't realize the time.
The door to the offices where my office was, containing my car keys, wallet and cell phone, was locked. No one was left in the building. All the doors were locked.