There is nothing in the article to support the "while under interrogation" claim.
They were still in our custody. While not completely improbably, I don't think these guys would be able to cause the blunt force trauma that exaccerabted their conditions, so, in that case, that means someone else did.
I sincerely hope we are not resorting to physical tourture.
Further, there is nothing in the article to support the claim that the "torture" was carried out by U.S. military personnel. Afghan troops may well be responsible for the torture, but this article doesn't make it clear at all. And, maybe, these guys were in "general population" and got pummeled by their islamonazi friends because it was thought that they were cooperating with us too much.