WARSAW, Poland (AP) — A teenage student attacked classmates with a knife at a high school in northeastern Poland and injured three of them on Wednesday, police said.

The attack took place during lessons at the high school in the town of Kadzidlo, local police spokeswoman Katarzyna Kucharska said.

Two of the teenage victims — one female and one male — were hospitalized in serious condition, and the other one was treated on the spot, Kucharska said.

The 18-year-old attacker has been apprehended and the police and prosecutors are investigating, said Elzbieta Lukasiewicz, a prosecutor in the nearby city of Ostroleka.

School attacks are very rare in Poland.