preplašiti

1. to scare; to frighten badly
   Grmljavina je preplašila decu. — The thunder frightened the children.
   Nemoj da me tako preplašiš! — Don't scare me like that!
2. (with se) to get scared; to take fright
   Pas se preplašio od vatrometa i pobegao. — The dog got scared by the fireworks and ran off.

The cause of fear takes od + genitive: preplašiti se od psa.