Killed a lot of Americans (4)
I believe the answer is:
slew
I believe this is a double definition.
'killed' is the first definition.
(historical past tense of slay)
'a lot of americans' is the second definition.
(I've seen this before)
(Other definitions for slew that I've seen before include "Greatly amused" , "Dispatched" , "Uncontrollable turn/slide" , "murdered" , "twisted position" .)