Three students were stabbed at a primary and middle school in Pirkkala in southwestern Finland on Tuesday, and the suspect, a student at the school, was arrested shortly afterwards, police said.

The three wounded did not sustain life-threatening injuries, police spokeswoman Nina Juurakko told AFP, adding that police “were investigating” media reports that the suspect had targeted girls in the attack.

The Vahajarvi school has around 1,250 students aged six to 15, but the ages of those injured were not known immediately.

“The suspect in the act of violence is a student of the Vahajarvi school,” police said in a statement, adding that they were alerted to the attack at 10:42am.

Finnish public broadcaster YLE said the suspect was believed to have “published a manifesto in which he describes the reasons for his act and the instrument he used”.

The broadcaster said it had seen the manifesto but “has not been able to verify” that it was written by the suspect.

YLE images showed several emergency vehicles parked outside the school, which was cordoned off while students remained locked inside as a precaution, it said.