Looks like it could have been a blocked barrel, as well.
My concern is that it happened because of some operator error. I would like to know what that reason was, so it does not happen on my weapon when I or my wife is shooting it.
I have shot my XDM over a thousand times, without a failure of any type. I hope to continue that record.
It hopefully did not harm the user, although it looks like it could have caused substantial hand or eye damage.