What’s the most terrifying 'We need to leave... now' gut feeling you’ve ever had?

There was a cheap semi-rundown hotel in a not-great neighborhood that I had stayed at during one of my trips early this year (a learning experience). It had been late when I arrived and there was no late-night staff apparently, so I did not see a single person before getting to my room where I punched in a keycode to open and lock the door. I thought I had heard at one point someone turning the door handle trying to get into the room, which freaked me out. Seriously considered changing hotels in the middle of the night, but I stuck it out.