The attacker used a bladed weapon, police said in a statement, adding that the injuries were not believed to be life-threatening.
Three pupils were injured in an attack at a school in southern Finland on Tuesday and a fellow student suspected of carrying out the assault has been apprehended, police said.
Police said they were investigating written material believed to have been published by the suspect prior to the incident, but did not elaborate on the content.
They did not state the age of the victims but said their parents had been informed.
Pupils at the Vahajarvi school in Pirkkala, some 180 kilometres (110 miles) north of Helsinki, range from pre-school age to ninth grade, according to its website.
