Parents and teenagers have been warned it could trigger a major emergency response.

Police are warning parents and teenagers that a viral TikTok game could trigger major emergency responses after a Sydney TAFE campus was plunged into lockdown when a student was spotted carrying a water pistol.

The alarm was raised at Campbelltown TAFE on Tuesday afternoon when a 16‑year‑old girl walked through the grounds holding the brightly coloured water pistol — later revealed to be part of a TikTok challenge known as “Senior Assassin”.

From a distance, staff believed she was carrying a real firearm, prompting security to lock down the campus and call police.

Senior Assassin is a viral TikTok game popular with high‑school students, usually Year 12s, where players “eliminate” each other using water pistols or other toy guns

In a TikTok video posted after the incident, NSW Police urged teens to rethink the trend, warning that officers have no way of knowing whether a reported weapon is fake.

“From a distance, these items can look very real,” an officer said.

“If someone reports a firearm to police, then we treat it as a genuine threat, and we respond accordingly. In that moment, we don’t know it’s just a game.”

“A bit of fun can very quickly become a very serious situation.”

Emergency services swarmed the Narellan Road campus just before 4.30pm, with hundreds of students ordered to hide under desks and tables as blinds were pulled down.

Police moved through classrooms and buildings to ensure everyone was safe.

Officers later spoke to the 16‑year‑old at a Campbelltown home around 7pm and seized the water pistol.

The lockdown was lifted once the campus was cleared, and students were allowed to be collected by family members.

Police say the incident is a stark reminder that imitation weapons — even those used in social‑media games — can trigger full‑scale emergency responses.