My Calico girl was once shocked just like your kitty. The new neighbor's dog got out of his yard and came to our patio door. Patches totally freaked out and turned around in a hurry to get away. She ran right into the bookcase. She had the same look of terror you are describing. But after much consolation, she was alright.
(She wouldn't go near that door for weeks).
HOWEVER, if you notice anything unusual after a time tonight, I would definitely take Karen's advise and call a vet on an
emergency basis.