Today the workday in our physics building was rudely interrupted by the police. Apparently Chlorine gas leaked somewhere and everyone had to leave the building. Or wasn't allowed in in the first place, since it was early morning. For an hour everyone was standing around, first outside, then we were allowed into a small part of the building.
All things considered it was slightly exiting and a nice variation on the fairly common fire alarm. Usually that happens without the police and lasts no longer than 30 minutes.