MINNEAPOLIS (AP) — The Minneapolis School District says it won't tolerate violence, after four incidents of students at alternative schools assaulting staff members in recent months.

Police say a 14-year-old boy was arrested Thursday in the assault of a female teacher at Harrison Education Center.

The Star Tribune reports two other assaults occurred at Harrison, which serves students with behavioral and emotional needs.

On December 7th, Harrison Principal Monica Fabre was assaulted by a 17-year-old girl, who was arrested. Fabre says she's dealing with a concussion and hopes to return to work soon. Police say that the next day, an 18-year-old male student was arrested for allegedly assaulting a 29-year-old male paraprofessional.

The fourth assault happened in November at River Bend, a K-8 school. A 13-year-old girl was arrested for assaulting a female teacher.