Well those are all KillingFloor Soldiers and Specimens in psk and tga file formats. You'll need MilkShape 3d (1.8.4) or 3d Studio Max + psk importer, or Blender 2.5 whith psk importer in order to use those.
There are 39 character models (38 soldiers + 1 trader), I have included all the specimens (normal, circus, halloween and xmas)
Download the Soldiers
Downoad All the Specimens