What are people thinking?!!

The other night, Nate and I were sitting down watching a movie at about 10:30 at night and we heard people out in the hall.  At first we didn't think anything of it, then we heard a loud banging and clattering noise and some laughing and yelling and then people running.  It was really weird, usually we don't hear anything in our apartment.  So I went to look out the peak hole and didn't see anything so I went to sit back down. Next thing we know, the fire alarm for the entire building is going off.  A noise that really makes you want to leave the building. 

I didn't really think much of it since this seems to happen a lot and then by the time you get half way down their stair well (coming from the top level - 7th floor), the security guard usually meets you and tells you to go back up.  So we weren't in a big hurry to leave.  We grabbed a few of our important items; phones, computers, camera... and headed down the stairs.  Well as soon as we opened the door, we were in a cloud of white smoke that choked you as soon as you took a breath. You couldn't see more that 10ft in front of you.  But it was weird, it didn't seem so much as smoke but we didn't know what it was.  At this point we were hurrying outside.  When we got outside, there were about 5 fire trucks pulling up to our building.  We were starting to get pretty nervous.  After about an hour outside, we finally were allowed back in the building and discovered that the cause of all of this was that someone had taken the fire extinguisher and sprayed it right in front of our door all the way down the hall way...which ended up causing the fire alarms to go off.  As you can kind of see from the pictures...the walls, the doors, and the ground were covered with the white chemical, as were our throats and lungs I'm sure.  What are people thinking?!!