Polish police have debunked social media threats of coordinated school attacks, arresting multiple teenagers for spreading hoaxes amid a wave of knife assaults in schools.

Authorities confirmed no credible evidence of a planned "bloody Friday" challenge after a video circulating online alleged attacks on schools across the Mazovia region. Police in Przasnysz detained a 17-year-old suspected of creating an AI-generated video threatening a massacre at a local high school, while officers in Szczytno arrested a 16-year-old who filmed himself threatening a school attack, claiming it was a joke. A third teen, 17, was detained in Sierpc after allegedly discussing plans to "do something bad" at his school; police seized two knives and his phone, which contained searches about planned attacks.

National Police Commander-in-Chief Marek Boroń announced reinforced patrols around schools on Friday, stating officers would work with principals and local authorities to ensure security. Some schools in Mazovia, including in Wyszków, Pułtusk, and Ciechanów, canceled classes as a precaution, though officials emphasized the closures were not directly linked to the debunked challenge. The Interior Ministry and police urged the public to rely only on verified sources and warned that deliberately spreading panic could result in criminal charges.

The hoax threats followed two knife attacks this week: a 19-year-old injured nine people at a vocational school in Ostrołęka on Wednesday, and a 15-year-old killed a 37-year-old school employee and wounded two others in Leszczydole-Nowinach on Thursday. Prime Minister Donald Tusk had previously warned of a "grim phenomenon of imitation" in the wake of the attacks.