Norwich ― Norwich Free Academy has never held a drill testing the evacuation of its football stadium, let alone a packed one filled with two teams, band members, cheerleaders and fans.

But on Friday night, such a real-world operation was carried out smoothly after FBI agents detected a threat posted on social media.

“We do tabletop evacuation (plans) with different scenarios,” NFA Head of School Nathan Quesnel said Monday. “But not actually drilling that.”

At approximately 8:50 p.m., as the NFA team clung to a 33-32 lead over Fairfield Warde High School and the Norwich school’s fans were poised to celebrate the season’s first win, the FBI’s national threat specialist team alerted police that they had discovered a Snapchat post of a picture taken from the NFA stands.

The post included an active threat to commit a shooting, Norwich police said.

Four Norwich police officers already were at the game providing routine security, and seven additional officers and a patrol supervisor were called in, along with two Norwich police school resource officers and the NFA campus safety team.

The teams, cheerleaders, band and spectators all were evacuated as officers quickly identified and located a juvenile girl who attends Norwich Public Schools. She was charged with breach of peace, first-degree threatening and second-degree reckless endangerment.

Norwich Public Schools Acting Superintendent Susan Lessard said the student was suspended immediately pending the school district’s disciplinary procedures. The student and her guardians will meet with the Norwich school board’s expulsion committee for a closed-door session not yet scheduled.

Quesnel address the NFA student body Monday morning.

“I expressed that I had three emotions as a result of this: gratitude, anger and hope,” Quesnel said.

He and Lessard both thanked Norwich police and emergency responders for their quick actions and assisting with the orderly evacuation and identification of the student.

“We’re really fortunate to have the partners we have at the Norwich Police Department and campus safety,” Quesnel said. “Our kids responded really well.”

Quesnel said his anger was for the hundreds of fans, the football players and supporters for the way the game had to end. NFA received the 1-point victory, but Quesnel said fans had been poised to erupt with excitement at the thrilling outcome.

He said he conveyed to students Monday morning that authorities will take all such potential threats seriously, and that any threatening or inappropriate posts on social media will be seen and tracked, with the poster identified.

Lessard said she and Quesnel discussed ways the two school systems can cooperate to improve security and response to issues that arise.

“There’s a big message,” Quesnel said. “‘Not in our school. Not in our community.’ Our kids don’t want this. Our kids want to be safe. They want to be at football games, and only by them coming together can we put a stop to this.”

c.bessette@theday.com