Ten people, including five students, two teachers and two bystanders, were injured in a knife attack at a vocational school in Ostroleka, Poland.

Police detained a 19-year-old student suspected of carrying out the attack with a machete about 20 minutes after it began.

Nine people were taken to hospitals, but authorities said none of the injuries were life-threatening, while the suspect also suffered self-inflicted injuries.

Students barricaded themselves inside classrooms for protection before being evacuated, and bomb disposal experts searched the suspect’s backpack, USN has reported.

The motive remains unclear, and authorities closed all schools in Ostroleka as police continued investigating the rare attack.