No, of course it's true!
What we know about American schools is only the big stories that make the news, ie multiple deaths. I read somewhere , and it sounded very plausible, that those things only made the news if it was in a white, middle-class school, where people did not expect those things to happen.
I read this in James Garbarino's book, Lost Boys
, a book I recommend. It's not about schools, and it's not just a long list of violent facts, it's a very humane description of the author's personal experience in helping violent boys.
In France pupils have no guns, but in difficult neighborhoods they bring knives, and use them.
And to return to McCarthy's list of teachers' concerns, teachers now fear for themselves as well. In some schools in France spitting on teachers is common, so you can imagine that being called "Sir" or "Ma'am" is not too strictly enforced. Several French teachers have been stabbed by their students in front of a whole class of onlookers, etc...
Those things only make the news occasionally, usually there is a lid put on all this.