Minneapolis police are on the lookout for a man and woman who they say boarded a school bus in the McKinley neighborhood last week and assaulted an 11-year-old student.

The suspects, whose age and names haven’t been released, are being sought in the attack aboard a bus that had stopped in the area of 34th and Aldrich avenues N., a few blocks west of Cityview Community School. The assault occurred about 4:21 p.m. Friday, police say.

A woman who says her children witnessed the attack, in which the adult suspects allegedly confronted the boy, posted on Facebook that the pair pulled the boy’s hair and spit on him, and also punched several students seated nearby. A motive for the attack was unknown.

The victim was taken to North Memorial Medical Center with minor injuries, police said. It wasn’t immediately clear which school the students aboard attend.

Police have so far released few details about the incident, which is being investigated by the department’s juvenile division.

A spokesman for the school district didn’t immediately respond to a request for comment on Monday afternoon.