And there government wont do dick about it.
Sure they will. They will have a reasoned response to the problem and the gloves will be taken off to a degree. Their LE has been training for this type of incident and they will not stop at finding justice until it is done.
They have a massive problem. They have let millions of folks into their country who will never assimilate to their culture. If they over react they will make their problem worse, same thing applies to under reacting.
Right now, all that can be done is to be vigilant, tend to the wounded and comfort the families of the fallen. Vengeance and justice will come later.