Poland’s ‘Bloody Friday’ school threats prompt big police operation

Thousands of Polish police officers visited schools nationwide on Friday in an effort to reassure pupils after two teenage stabbing sprees in as many days sparked rumours of a “Bloody Friday” of attacks. Social media in Poland has been filled with talk ‌of a supposed online challenge that could be behind the attacks and which would end with a bloodbath at schools on Friday, but police said their i