"Turn yourselves in now and we'll go easy on you," you say. "Hey!" says the fourth thug. "No one goes easy on us except on Sunday mornings!" "Yeah!" say the other thugs, rushing you as one before you have a chance to think twice about the absurdity of their statements.
Work with the Moonbrook Brigade to capture these thugs. Hold off the thugs by yourself. You don't need the help of a brigade of idiots. Just start killing the thugs. They obviously aren't amenable to capture at this point.