How about one of these new 'Tazer' guns that zaps an electric charge at the assailant a'la StarWars style, with no physical contact?!
It seems there are a number of avenues here to follow,and only with the advice of the best professionals in this type of business.
At the same time, when these solutions are found, keep them away from the press and just demonstrated to the crews involved.
An element of surprise is needed as well as tactical force.