MILFORD - Students were dismissed early Tuesday after pepper spray was released at Lauralton Hall in Milford.
Officials say it happened in the main lobby around 10:15 a.m. between classes, so several students were in the area.
About 30 to 40 students were affected, and 10 of them were taken to the hospital for further evaluation.
Officials say Lauralton Hall allows its students to carry pepper spray since many take the nearby train to and from school.
Police are calling this an accident and say there was no target.
Fire officials say crews ventilated the affected building and have determined it is safe to resume classes.