These players are inhabiting the Kopa military compound and aim-hack killing anyone who comes anywhere near the area.
Another player and myself were killed instantly at the same time out of nowhere at around 1:45 A.M EST, just south-west of the compound near the metal fence that runs around the perimeter of it.
I respawned and made my way back towards that area. As soon as I got close enough to see Kopa, I was killed instantly again. My location was in between the river and the railway, just south-west of the bridge south of Gliniska. This happened around 2:36 A.M. EST.
I respawned a second time, miraculously, right near where I was killed along the river. I was now on the OTHER side of the river this time, inside thick brush -- BAM -- killed instantly yet again.
I've played this game since 2014. This wasn't a skilled sniper. This was someone aim-hacking, hitting perfect head shots from far beyond what's possible.