Central Connecticut State University was thrown into a panic yesterday when reports of an armed person on the premises sent the campus into a lockdown. After three hours of worry, it was over: a suspect had been arrested, no weapon was found, and police say there was never a threat in the first place. What gives?

The person at the center of the commotion, the 21-year-old son of geography professor Peter Kyem, was carrying a prop sword—for his Halloween costume. Four days after the holiday. CBS Connecticut reports:

The elder Kyem said his son attended a party at the University of Connecticut for three days without a change of clothes and returned to campus Monday still wearing his Halloween costume, which was a ninja.

Well, that's a relief. At least CCSU had those ninja-attack procedures in place.

[image, of tourists dressed as ninjas in Tokyo, via AP]