http://www.jasenovac.info/cd/galerija/arhivrs/index_en.html
(Photos of graphic nature, please be advised)
http://www.jasenovac.info/cd/galerija/arhivrs/unutar/img0061.jpg
(Photo of "Srbosjek" (Serb-slicer) consisted of a metal knife-blade strapped with ledder belt otno wrist for more efficient slaughter of Serbs)
http://www.jasenovac.info/cd/galerija/djecakozare/1/index_en.html
http://www.jasenovac.info/cd/galerija/djecakozare/2/index_en.html
http://www.jasenovac.info/cd/galerija/djecakozare/3/index_en.html
(Photos of Serb children starved to death in Jasenovac, captured during Kosara region-offensive of Croates.)
As for the children and people of Kozara, I heard it was mainly the German soldiers, with aid of Croats, who encircled the Serbs around that mountainous area and then gradually tightened the circle until the Serbs were all trapped up a mountain.