 You all walk on your roof multiple times a year with a steeper slope than that roof there. Oh, and it's a trained sniper team. Got news for you. They can fire and set up on a sloped roof just like the two sniper teams did on two sloped roofs right there on the opposite side of that field. There is no excuse for that. Now you throw in there that they knew the shooter was there 30 minutes ahead of time?