Cadmus Labs is a private genetics research facility in Washington DC. A few months ago, some of the materials it was having delivered got it put on a Justice League watchlist. 

It took a while to rise to the top of their priority list. They're busy people. 

So, when a fire started on the ground floor and quickly spread through the building, it wasn't the Justice League who came to see what evidence of illegal activity they could snatch from the flames—after rescuing the trapped scientists, of course. They're heroes, after all.