shock,
revelation, bolt from the blue, disclosure, bombshell (informal), shocker
(informal)
astonishment,
amazement, wonder, disbelief, shock
alarm,
astonish, startle, astound, amaze, flabbergast (informal), stagger, stun, shock,
take the wind out of your sails, take aback, bowl over, take by surprise, render
speechless, daze, dumbfound, knock for six (UK, informal)
catch
unawares, catch napping, take by surprise, burst in on, intrude on, come
upon, interrupt, disturb, disrupt