The Stonington High School prom was shortened this weekend after somebody sprayed an irritant similar to pepper spray into the air.
Three students were hospitalized after being exposed to it.
The school principal says the students were treated and released from the hospital on Sunday.
Adults were later allowed into the ballroom at the Mystic Marriott Hotel to collect personal belongings.
Groton and Stonington police departments are investigating the incident. It’s not clear what the substance was. No one was arrested.