All abusers are cowards. Unfortunately that's not quite true. It'd make life much easier if it was.

In a moral sense, maybe, but not when it comes to physical violence. The abuse is cowardly, true enough, but that's quite another matter.

Safety is a lot more of a priority than trying to get justice in this kind of situation. But when it's calmed down if there's any way you can take the police authorities who have failed so shockingly to dfo their duty to the cleaners, that might be the most important thing to do - if anything they sound like the major abusers in this case.