A 19-year-old student injured eight people in an attack at a vocational school in Ostroleka, northern Poland, on Wednesday, authorities said.

Police said the attack took place at about 11 a.m. local time at Vocational School Complex No. 4, about 120 kilometres northeast of Warsaw. Four students, two teachers and two passersby were hurt, prosecutors’ spokesperson Elzbieta Edyta Lukasiewicz told the Polish news agency PAP.

None of the injuries was life-threatening, she said, though one person was seriously wounded. Some victims were taken to hospital by helicopter.

Police said the suspect fled and was arrested on a riverbank less than one kilometre from the school. Prosecutors said he was wounded during the arrest as a result of self-mutilation. Authorities have given no motive and no details of the weapon, and have identified him only by first name and initial under Polish privacy law.

Ostroleka Mayor Pawel Niewiadomski said the situation was under control. The school will stay closed during the investigation, and psychological support will be offered to those affected.