So what does this bear do in this office? Any wildlife specialist will give the instant, simple and not really informative answer to this question: the bear is looking for food. Such kind of things are happen surprisingly (and unfortunately, mostly for the bears) often in the places bordering the bears’ natural habitats.
In this particular case, which have taken place in one of the oil drilling sites in the Northern Canada not so long ago, the black bear wandered to the drillers’ camp driven by the hunger. Eventually, it managed to enter the office trailer and wreaked not so much havoc considering the elephant in the china shop situation. Nobody got hurt this time.
Black bears are not as much aggressive like the polar ones. They are only dangerous if they are hurt, got rabies or if it is the mother protecting its cubs. You can scare them run by screaming at them, if you have big enough cojones to scream at the bear’s face, of course.
However, despite the fact the black bear encounters in the most cases are far from being deadly dangerous for humans, they are still dangerous for the bears. Even if the bear haven’t been killed on its first visit to the camp or dwelling, it could develop a habit to visit regularly to ravage the trash containers, search for unattended food, etc. Eventually, it will lead to tragedy, either for humans, but most commonly for the bear.