Because, you know, this:
A New Jersey light rail shutdown was due to an umbrella that was mistaken for an assault rifle.
Someone had reported to police that a man wearing black pants, white dress shirt, with a cast on his arm was "armed with a long barrel assault weapon" had gotten on the train.
... Police started scouring surveillance videos and was able to track down the man at the Exchange Place station.
Apparently, they were able to determine that the only "weapon" the man had was the umbrella he planned to use later in the day to fight off rain from hitting him.
... looks so much like this: