It happened around 8:30 a.m. on May 17, Ridley Township police wrote in a release. Witnesses reported a person with a gun hiding in some bushes near Notre Dame DeLourdes School, 990 Fairview Road, they said.
Ridley and Nether Providence police responded and locked down the school, as well as nearby Grace Park Elementary, 1097 7th Ave, authorities wrote.
Investigators soon found the "gunman," who turned out to be playing a game called "Senior Assassins," according to police. The prankster said he was targeting a friend across Michigan Avenue, "not thinking it would cause alarm to the school behind him," officials wrote.
Police say that public pranks involving water guns are ill-advised "in today’s day and age."
"This is not a good idea and could end in disaster," said Nether Providence police. "In addition, these senseless acts pull valuable resources away from other emergency calls."
A similar senior tradition at Pennridge High School in Bucks County has prompted police criticism in recent months.
The Pennridge rendition of the game, called "Jackal" by participants, has led to "calls for armed subjects, burglaries-in-progress, stalking, reckless driving, and suspicious persons," Hilltown Township police said earlier this year.
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