fire!! fire!!

Last night I woke up of a extremly loud tone.
it was biiping, and I couldn't understand what it was. First I thought it was the alarm on mye telephone so I looked at my phone and it was only 3.am, not the time my alarm was set. after a cople of moments trying to understand what it was, I got that it was the fire alarm. and it was going of in the whole building.
I went out to the street, and the security guards were outside our building. There was appearantly no fire, but no one turned of the alarm. after a while the fire fighters came, but they couldn't do much, 'cause there was no fire and didn't have the key for the fire alarm. After half an hour security got the alarm shut of, and we could go to sleep again....