I’m amazed that the ones doing the apprehending weren’t themselves charged with assault and battery, and unlawful detainment. Unless you’re certified LEO, you can’t do that.
Don’t spread false rumors. You can indeed make a citizen’s arrest.
Of course you can, however you had better have a good liability policy in case you make a mistake. You have the same powers to detain as an LEO, however they have much more protection.