Miami (AFP) - A four-year-old boy accidentally shot his mother in the back, leaving the passionately pro-gun woman badly wounded and facing possible charges, Florida officials said Wednesday.

Staunch gun advocate Jamie Gilt, 31, who just a day earlier had boasted online about her toddler's shooting prowess, was cruising down a major thoroughfare with her son in the back when he shot her on Tuesday. The bullet went through the seat cushion.

"Our investigation has revealed that the firearm was legally owned by the victim and the child came to possess the firearm without the victim's knowledge," Putnam County Sheriff's Office said in a statement.

Gilt, who is in a stable condition, was so badly wounded that police detectives have been unable to interview her from her hospital bed.

But they warned that she could face police action after they work out exactly how the boy -- who was unharmed and is now with relatives -- got his hands on the gun.

The weapon was a .45-caliber handgun the boy found on the floor of the pickup truck, NBC News said, citing police.

The mother and boy were on their way to pick up a horse, said police, who rushed to Gilt's aid after a police officer slowed to check why the vehicle had stopped.

Gilt, of Jacksonville, Florida promptly told police that her son, who has not been named, had accidentally shot her.

"Florida statute makes it a misdemeanor for a person to store or leave, on a premise under his or her control, a loaded firearm in such a manner that it is likely a child can gain access to the firearm," said the statement.

"Due to her medical condition, detectives have not been able to interview the victim and any decision on the filing of criminal charges will not come until after we speak with the victim."

What appears to be Gilt on Facebook shows she is a passionate supporter of the right to bear arms, including pictures of her with weapons and with a cowboy hat perched on her head.

On Monday she concluded a discussion on Facebook about possessing weapons for self-defense by boasting: "Even my 4-year-old gets jacked up to target shoot the .22."

The incident shines another damning spotlight on America's gun culture and Facebook users wasted little time in ridiculing Gilt.

One of her two Facebook pages -- a community page called "Jamie Gilt for Gun Sense" -- has a profile picture of Gilt with a long gun, black cowboy hat and staring intently into the camera.

"Model mom -- not!," wrote one Facebook user commenting on the photo.

Another added: "Please don't have anymore children."

"For your sake, I'm glad your son doesn't have better aim," said another user.

Both Facebook pages later appeared to have been taken down as Gilt's notoriety grew.