I'm thinking a fighter jet. The CIA had a small airforce at it's disposal and they had the authority to requisition whatever they wanted from the Armed Forces. It could come in low and fast and would probably lose it's wings on it's way through the building. Just a wild-assed guess on my part though.
Debris is still up there and can be seen with a powerful enough telescope. Also laser targets were set up for scientists. Dig and ye shall receive.