One person was hospitalized, and more than a dozen others were treated by medical personnel, Monday afternoon after a release of pepper spray at Park City High School, the Park City Fire District said.

According to Phyllis Suggett, assistant principal at PCHS, a group of teachers and students experienced chest pain and coughing at approximately 1:50 p.m., shortly after class ended for the day, and quickly left the building. The teachers and students did not know at the time what the substance was. Principal Roger Arbabi said a front office staffer pulled the fire alarm as a safety precaution after a teacher alerted the front office to the situation.

“We pull it when we need to evacuate the building,” Arbabi said. “It was just a judgment call on our part.”

The Park City Police Department and the Fire District responded to the school. At least three ambulances and four fire trucks were on scene. Hazmat responders were also present.

According to the Fire District, responders were initially summoned to investigate a potential gas leak. The substance causing the respiratory symptoms was later determined to be pepper spray.

Phil Kirk, a police captain, said a student admitted to releasing the pepper spray. The Park City School District and Police Department together will determine whether to take disciplinary action against the student.

Medical personnel treated 14 people on scene for respiratory distress, according to Tricia Hurd Hazelrigg, a spokeswoman for the Fire District. One additional person was transported to the hospital. Four other people reported symptoms after leaving the school.

Kasey Kirklen, a junior at the school, was one of the students who was treated after experiencing respiratory problems from the pepper spray. She said she and other students were on their hands and knees coughing uncontrollably when they walked into the spray.

“I couldn’t breathe,” she said. “It was serious and kind of scary for a second because you didn’t know what was happening.”

Events at the school were canceled for the evening, and the school remained closed until Tuesday morning, said Melinda Colton, a district spokeswoman.