The attack took place at a school outside Wyszków, northeast of the Polish capital, Warsaw, on Thursday morning.
According to the Gazeta Wyborcza newspaper, the perpetrator attacked the caretaker and a teacher with a knife. A principal who intervened was also reportedly injured. The 15-year-old was overpowered and then arrested by police.
The 37-year-old caretaker has died from his injuries, the PAP news agency reports.
On Wednesday, another violent incident occurred at a school just 50 kilometers to the north, in the town of Ostrołęka. At least eight people were injured in an attack with a sharp object, and a 19-year-old student was arrested.
