The officials said what happened next is not clear, but added that the force likely ran out of ammunition and that the militants captured several policemen and later killed them.
“...but added that the force likely ran out of ammunition...”
I recall the story of some troops in Afghanistan (maybe a freeper) that were told to take as much ammo as they could out on missions/patrols. So they tossed an extra dufflebag of magazines in.
After they had their first encounter they filled every nook & cranny in their Humvee - and pulling off panels to create new ones - with spare magazines.