There are three possible answers:
1) Yes (this is how I understood the OP)
definitely call the police. (Is there anyone, besides for Joseph, who disagrees in this situation?)
I agree that you must do whatever necessary to prevent the danger. If you must, you definitely call the police. But calling the authorities – while often the most comfortable approach – isn’t necessarily something you have to do. If you can burst into the room and stop the danger yourself, you may be obligated to do that rather than reporting.
Unless you are certain that there is danger, and that you would classify the abuser as a Roidef. In that case, you can probably לכתחילה call the authorities.