Emergency services are seen at the scene of a knife attack at the Adam Chetnik Vocational School Complex in Ostroleka, Poland. (EPA Images pic)

WARSAW: A 15-year-old former pupil killed one person and injured two others at a Polish primary school on Thursday, police said, just a day after a 19-year-old wounded 10 people including himself in an attack at another school.

Authorities said a 37-year-old woman who worked as a caretaker had died in the attack, which took place at around 7am in Leszczydol-Nowiny, in Wyszkow County northeast of Warsaw.

"She was the first person attacked with a sharp object," police spokeswoman Katarzyna Kucharska told private broadcaster TVN24. "The principal heard the screams and attempted to restrain the attacker, assisted by a teacher - both were injured," she said.