New boss fight with alliance tribe

Ok i have searched google and have found conflicting answers. But does anyone know if my tribe and my alliance's tribe go in the boss arena to fight the boss together, will both tribes unlock the tek engrams or will only the tribe of the one that killed the boss unlock it. I understand that the element is in the body and will have to be shared equally but i only want to know if both tribes unlock the engrams or only one tribe any info/links to sources will be greatly appreciated thanks.