Three of the dead were no-hook privates. Literally just starting their careers.
The scary part is that this was just a grass fire. Those happen all the time in training areas. You're firing tracers, explosives, etc. It's very, very easy to start a fire. They happen at least once a week during routine training like this. You call it in, range control takes care of it. They had no reason to expect this would be any different.
Then the wind changed and suddenly the fire was moving towards them at 100km/h.