Sounds like wounded insurgents have been booby-trapping themselves.
Our troops get near them and they release a grenade, roll off of a contact mine or something else along that line.
Kind of hard to unpin a grenade when you've got a bullet in your head...
Reminds me of what the Russian SWAT squads did when the Chechen loonies raided that theater in Moscow a while back. They didn't take chances in moving any of the terrorists while they were still alive; a bullet was put in each head.
It's ugly and brutal, but very effective in minimizing risk.
Of course, "better safe than sorry" is a concept that doesn't dawn on too many people outside of a combat situation...
