Group everyone involved into a room, stand in front of the only exit, and calmly announce that nobody gets out until you receive an explanation. State the facts neutrally as you know them, and ask if they are accurate.
Actually let people out once they have explained. There is no reason to start kicking ass until you have a complete picture.
Once you have a complete picture, decide whether it's time to start kicking ass, and by what method.
I'm going to assume you're not being literal, but FYI, I sat on a kidnapping jury that was essentially this. Don't trap people, even for a moment; it's quite illegal.
If you look at my posting history, you'll notice that I have little care for the laws of man. Do the right thing, always. If it's legal, good for the law. If it's illegal, break the law.
But break it properly, so that after you're done breaking it, it will take a long time for legalists to repair it and people have time to consider that they may be better off without it.
Now in this case, locking people in with you is excessive. But, making it clear that it's easier to say truth than to push you aside is appropriate.
Actually let people out once they have explained. There is no reason to start kicking ass until you have a complete picture.
Once you have a complete picture, decide whether it's time to start kicking ass, and by what method.