Got killed with my friend at NW airfield by invisible player. He just walked to my friend and killed him probably with an axe. No shots were heard. Then he walked to me (invisible) and killed ma also. When I hit escape to respawn I saw him looting my body. I do not know if cheaters are not using this glitch where sometimes zombies are invisible. It happeneed to me 2 times to meet invisible zombies and the only option was to run away.