They apparently decided not to secure the roof that the assassin ended up shooting from because it was sloped and so they were afraid.

I'm not making that up.

"That building in particular has a sloped roof, at its highest point. And so, there's a safety factor that would be considered there that we wouldn't want to put somebody up on a sloped roof. And so, the decision was made to secure the building, from inside," [U.S. Secret Service Director Kimberly Cheatle] said.

She's also trying to throw the local cops under the bus.

"In this particular instance, we did share support for that particular site and that the Secret Service was responsible for the inner perimeter," Cheatle said. "And then we sought assistance from our local counterparts for the outer perimeter. There was local police in that building -- there was local police in the area that were responsible for the outer perimeter of the building."