From this photo, his stance looks like he's fixing to fire a gun, but what is in his hand isn't so clear. From head on (which I presume is where the LEO is seeing him from), it might look more like a gun. Or less. Or, most likely, it's not that clear in the dark, but the total picture is enough to make the LEO think he's about to get shot. Or maybe you're telling me that this side view is what the second officer sees as his buddy is about to get shot. I see a BG who acts like he has a gun. After fleeing five miles from cops and wrestling himself free from one.
SHOOT.