Not a humane dispatch by the sound of it. One presumes the deer was in agony, and unless instantly dispatched by lethal shot, repeated beating about the head could only have added to its pain. They were equipped to deal with it, so one wonders why they did not use a firearm.
No doubt someone will declare that the agony of the beast was at maximum and a few blows about the head will not have been felt. Feel free. Have your point of view but mine is that they prolonged and caused further suffering. In two words, cruel ineptitude.