I seem to recall an incident the day my daughter was born that saw 3 large axe-wielding men bursting open doors in the maternity ward as alarms blazed across the hospital. And yes, it was my fault.
I heard "CODE RED! CODE RED! Connell 5" coming over the PA. I looked at my wife. "I know we are on the 5th floor. Not sure about the wing?" She assured me it was Connell all right. Ugh.
I peaked out the door. Nurses and orderlies were rushing past. Then the firefighters arrived in full gear. They initially trudged past us and went into other rooms, but then they turned around and made a B-line for us. They barged in and knocked around the place. Spent a lot longer with us than anywhere else. Then one of them noticed I was holding a camera. "Could I see that?"
He took the thing apart and eventually pronounced "Yep, this is our culprit right here. The flash set off the detector." I just remember feeling smaller and smaller and wishing I could disappear into the floor.
I'm guessing it was some sort of photoelectric sensor that detects the light coming from a fire? So not your usual smoke detector. But I honestly don't know.