Having read Rory's and Patrick's books, and having some experience at such things, I highly recommend them both. Rory has multiple books, but "Facing Violence" and "Conflict Communications" are the most applicable for this.

There are many books on the subject, and most are so basic and incomplete that they are not useful. One other I do recommend is Pat McNamara's "Sentinel". It talks a lot about being prepared as well as reacting. (disclaimer: I have known McNamara personally for about 30 years and consider him a friend. However, my recommendation is an objective one).