I have recently read a report which blames many of the Glock .40 failures on the fact that (at least in certain models) the .40 fires from an unsupported chamber. It seems there have been a great many cartridge blowouts and deformed cartridges which have caused malfunction.

I am truly sorry to hear of the loss resulting from the incident posted in the OP. I pray God keep and protect the fallen and heal the families.