(n.) An ambush.

ambuscade ambushment assail assault astonish attack blind blitz booby trap bushwhack catch off-guard catch unawares come at come down on come from behind come upon unexpectedly cover crack down on descend on descend upon do the unexpected drop in on ensnare entrap fall on fall upon gang up on go at go for harry have at hideout hit hit like lightning intercept jump land on lay at lay for lay hands on lay into lay wait for lie in ambush lie in wait light into lure lurk lurking hole mug pitch into pounce upon pound pull up short retreat sail into set on set upon shadowing snare spring a surprise spring upon stalking-horse strike surprise surveillance swoop down on take by surprise take short take the offensive take unawares trap wade into waylay