Image copyright Facebook Image caption Police say an officer mistakenly shot her with a live round of ammunition

A Florida woman attending a police seminar was shot dead during a demonstration on how to use a gun.

Mary Knowlton, 73, was participating in a role-playing exercise when an officer mistakenly shot her with a live round, the Punta Gorda Police Department said.

She was rushed to a nearby hospital, where she was pronounced dead.

The police department did not release the name of the officer involved, but said he had been placed on administrative leave.

Mrs Knowlton, a librarian, was one of 35 students participating in a two-hour community training class hosted by the police academy in Punta Gorda, Florida on Tuesday.

She was taking part in a "shoot/don't shoot" exercise, in which participants decide whether or not to use simulated lethal force when she was hit with live ammunition.

"I am devastated for everyone involved in this unimaginable event,'' Police Chief Tom Lewis said at a news conference.

`"If you pray, please pray for Mary's family, and for the officers who were involved. Everyone involved in this accident is in a state of overwhelming shock and grief.'"

The Florida Department of Law Enforcement is investigation the incident, Mr Lewis said.