we're about less than a hundred yards from the hospital. that is what is left of the main hospital and other buildings close by. and they have human shields. in this broken city, it's thought there are still around 2,000 civilians. america's allies on the ground are out for revenge. many have lost family members to isis. and with them is an american volunteer, mike hogan from phoenix, arizona, who was a waiter before he came here six months ago. have you killed any isis fighters during the action that you have seen? >> no, between you and me, i'm hoping to. i have had friends die here. i want to get even before i get out of here. >> reporter: they've already retaken clock tower circle where isis acted out its perverted interpretation of islam. this place used to be a landmark in a peaceful city. then isis turned it into a killing field.