A pro-gun activist from Florida, US, has been shot in the back by her four-year-old son while she was driving.

Jamie Gilt is a staunch gun advocate and recently posted on her Facebook page, ‘Jamie Gilt for Gun Sense’, that her young son “gets jacked up to target shoot with the .22”.

Ms Gilt was driving with a horse trailer on the back of her car when her son, who was in the backseat, picked up her .45 calibre shot gun from the floor and fired a shot.

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The bullet went through the back of Ms Gilt’s seat and into her back, hitting her while she was driving the car, Jacksonville.com reported.

Fortunately, a police officer driving behind Ms Gilt noticed her steering become erratic.

“As the deputy slowed to check on the vehicle, he observed an adult female in the driver’s seat motioning to him as if she needed assistance,” Putman County Sheriff’s office spokesman Joseph Wells said.

“The deputy ran to the vehicle and quickly determined that the driver had been shot.”

Ms Gilt was taken to hospital and is in a stable condition. Mr Wells told media the boy was not strapped into his baby seat when he opened the car.

Ms Gilt’s Facebook page has been disabled after it was flooded with angry comments about gun safety and children.

It is believed the incident is being treated as an accident and the child will not face charges, although it is not yet known if Ms Gilt will face any.