A former Twin Cities woman was fatally shot while participating in a Citizens Academy exercise at police headquarters in her adopted city on Florida’s southern Gulf Coast, authorities said.

“In a horrible accident,” Mary Knowlton, 73, of Punta Gorda, “was mistakenly struck with a live round” Tuesday evening after she and another of the 35 academy participants were randomly chosen for a “shoot-don’t shoot” role-playing exercise that involves decisions about when to use lethal force, said Police Chief Tom Lewis.

Knowlton was taken to Lee Memorial Hospital in nearby Fort Myers and pronounced dead, the chief said.

Before retiring, Knowlton was the librarian at Parkview Elementary School in Rosemount from 1988 to 2004, then was a substitute librarian at other schools in the Rosemount-Apple Valley-Eagan schools through 2013, a district spokesman said. Knowlton also worked for the Scott County Library in the 1980s at the Prior Lake branch before taking over at Parkview, that county’s library director said.

“Mary Knowlton was the center of our school at Parkview, and she made the library the heart of the building,” said Parkview Principal Nicole Frovik.

One of Knowlton’s two sons said in an interview with the Associated Press at his parents’ home that he will forgive the officer who fired.

“There’s too much hate in this world. In America, we always feel like we need revenge and it doesn’t solve anything,” Steve Knowlton said. “I obviously can’t say it’s easy to forgive, but it needs to be done. … I forgive him.”

Mary Knowlton originally was from Austin, Minn., where she went to high school and graduated in 1961. She then studied at St. Olaf College, the University of Minnesota and Minnesota State University, Mankato, among other institutions. She also served on the Scott County Library Board from 1993 to 2001.

Mary and her husband, Gary Knowlton, relocated to Punta Gorda from Prior Lake, where they had lived since 1973.

“Our entire Police Department and all of our city leaders are absolutely devastated for everyone involved in this unimaginable event,” Lewis said. “… Everyone involved is in a state of overwhelming shock and grief.”

In a follow-up news conference Wednesday afternoon, the chief said the officer who fired the fatal shot, identified as Lee Coel, is “very stricken” over the incident. Lewis said he and other members of the department were in the room at the time of the shooting.

The chief also described the weapon as a revolver that is not a service weapon and had been used in previous training situations, but he declined to say anything more about the firearm. Lewis said that potentially lethal weapons will “absolutely not” be used in future demonstrations of this sort.

Lewis offered no other specifics, saying that investigators “must take great care to not jeopardize the investigation. As the investigation continues … we will be as transparent as possible, and release that information.”

Photographer Sue Paquin, who was covering the event for the Charlotte Sun, said the officer was playing the “bad guy” when he fired several rounds, according to the newspaper’s Facebook page.

Officials from the Florida Department of Law Enforcement are investigating, Lewis said. Coel has been placed on administrative leave.

Punta Gorda, a city north of Fort Myers with a population of roughly 16,000, describes its Citizens Academy as a free eight-session course of interactive classes “designed to give citizens an up-close and personal look at how city government functions and helps shape our community.”

A proud Minnesotan

Knowlton stayed close to her profession through the Friends of the Punta Gorda Library, serving as its president for a time and holding a position on its board at the time of her death.

“I can’t even begin to tell you, the number of civic organizations she was involved in,” said Katie Mazzi, who succeeded Knowlton as president of the Friends of the Punta Gorda Library. Mazzi said Knowlton “loved being from Minnesota.”

Mazzi said she and others are left wondering how “one of these freaky, freaky accidents” could have occurred. “The Punta Gorda Police Department is an excellent police department,” she added.

Along with Gary, Knowlton’s husband of 55 years, and son Steve, her survivors include son William.