People are stupid. I worked a pretty large natural gas explosion investigation at a medium sized suburban commercial building. There were multiple 911 calls reporting a potential leak, but when the fire department showed up, almost no one had evacuated. People were still in their yoga class or catching up on some work on a Saturday. Thankfully it didn't blow up until shortly after the fire department got there and no one was injured.

Of course there is the possibility that the company are shit bags and didn't allow shut downs or evacuation. But it isn't a certainty.