panic

(noun) an overwhelming feeling of fear and anxiety. Synonyms: terror, affright.

(noun) sudden mass fear and anxiety over anticipated events. Synonyms: scare. Examples: "Panic in the stock market." "A war scare." "A bomb scare led them to evacuate the building."

(verb) be overcome by a sudden fear. Example: "The students panicked when told that final exams were less than a week away."

(verb) cause sudden fear in or fill with sudden panic. Example: "The mere thought of an isolation cell panicked the prisoners."