Polish police have detained 76 people and checked nearly 50,000 schools across the country following a wave of attacks that has raised fears of copycat violence among young people.
The latest incident happened on Saturday at about 12:30pm local time, when a 21-year-old woman used a "dangerous object" to attack a 17-year-old woman at a higher education college in Warsaw, according to Jakub Filipiak, a Warsaw police spokesman. Two other people, aged 17 and 24, were also hurt. Filipiak said one person was taken to hospital with non-life-threatening injuries, while the other two did not require hospitalisation.
The attacker, who police said did not know her victims and was a student at the school, was arrested. National newspaper Wyborcza identified the institution as TEB Edukacja, a post-secondary school. A Warsaw police spokesperson said they could not confirm whether the incident was related to the two earlier attacks this week.
Those attacks began on Wednesday, when a 19-year-old student injured nine people at a vocational school in the Mazovian province of central Poland. A day later, a 15-year-old fatally stabbed a female caretaker at the John-Paul II primary school in Leszczydol-Nowiny and wounded two other adults.
The violence has prompted a broad official response. On Friday, some schools suspended classes, many parents kept children at home, and police patrols were deployed to educational institutions. Prime Minister Donald Tusk said ahead of the operation: "When it comes to the safety of Polish children and peace in our schools, there is no room for compromise."
Local media, citing a police spokesperson, reported that authorities had information suggesting this week's incidents could be related to an internet challenge.