BOSTON -- Several people were treated Tuesday after being exposed to pepper spray at a Boston middle school.

The incident happened early Tuesday afternoon at the Martin Luther King Jr. Middle School on Maxwell Street in Boston's Dorchester neighborhood. A 15-year-old was charged with assault after allegedly releasing the spray in the school.

Four students were treated at the scene by EMS after complaining of eye irritation. Two were later taken to Boston Medical Center.

The school was evacuated.