The measures follow an operation on Oct. 9, called 'Bloody Friday,' where police inspected over 10,000 schools in response to coordinated threats on social media. Officers detained up to 15 teenagers for possessing knives or issuing death threats. The current wave of violence began on Oct. 7 when a 19 year old injured 10 people in Ostrołęka. Polish Interior Minister Marcin Kierwiński stated that at least one suspect had used the internet to research how to carry out attacks.
