It is true that you can run out of vacuum and lose power brakes but that did not happen in this case.

Not only did I have power brakes but the anti-lock kicked in as well (that part kinda surprized me). After a few seconds of tires squeeling and anti-lock brakes chattering the car stoped just fine. I did a quick underwear check and then got out of the car and moved the fallen tree. It all turned out Ok except that I had to use gas to restart the car (ohhh the humanity).