An eight-year-old student took a kitchen knife to a central Minnesota elementary school and attacked three other children, authorities say.
Chief Perry Beise said the victims - aged eight, nine and 13 - suffered "superficial wounds" requiring stitches in the attack before class started on Monday morning at Pleasantview Elementary in Sauk Rapids.
No one else was hurt.
School Superintendent Bruce Watkins said the boy lashed out at the other students until an adult intervened.
Mr Beise said the boy was interviewed by police and released to his parents.
The case will be forwarded to the county prosecutor's office.
One of the injured children is a seventh-grader who was waiting to catch a transfer bus. The other two are Pleasantview Elementary students.
Police in Sauk Rapids have not returned a phone message seeking comment.