Those folks lay it on the line daily (sorry for the cliche'). I would hope that the citizens would help by providing as much information as they have. If it becomes more serious, I would think it would be appropriate to enlist the assistance of the Texas Nat'l Guard. Don't know if Chuck Norris would be of any help here or not.
Notice I am trying not to suggest that they should seek assistance from the feds, except perhaps the FBI. I would expect the FBI in any city to have an interest in gang activity, which is essentially organized crime.
I do take seriously the threat to the police officers, but I can't help wondering whether FBI officers are eligible for membership in the Oath Keepers.
Regards,
D-Ray