March 10, 2010 -- Mistaking a loaded gun for a video game controller, a 3-year-old in Tennessee accidentally shot and killed herself, officials said.

Cheyenne Alexis McKeehan of Norene, Tenn., shot herself Sunday night after her stepfather left his loaded Smith & Wesson handgun out on a table, Wilson County Sheriff Terry Ashe said.

Cheyenne's mother told police officers that the child was used to playing a shooting game with the Nintendo Wii video game console and likely confused the real gun with the realistic-looking black toy gun, the sheriff said.

"The unfortunate thing is that this Nintendo game called Wii had what looks like a solid black, basically automatic-looking type mechanism that operates the game," he said. "Unfortunately, the stepdad also had a .380 caliber black Smith & Wesson. The child was used to playing the video game."

Cheyenne's stepfather, Douglas Cronberger, 32, owned a semi-automatic pistol that he normally kept in a secure location, out of the reach of Cheyenne and the couple's 1-year-old child, Ashe said. But after taking it out to investigate a possible prowler, Cronberger left it on a table and forgot about it, officials said.

Law Enforcement: If You're a Gun Owner, You Have to Be Responsible

When Cheyenne fired the gun, Ashe said, her mother, Tina Ann Cronberger, 32, was within three feet of her child. Cheyenne was pronounced dead on arrival at a local hospital.

"We're not looking at criminal intent," Ashe said, adding that no criminal charges have been filed. "There was a terrible lapse of judgment here."

He said that in his years in law enforcement, this wasn't the first tragedy he'd seen involving children and guns, but Cheyenne was the youngest victim he had seen.

"If you're a gun owner, you have to be responsible about how you store your weapon, especially if you have children," Ashe said. But he added that he hopes this incident causes others to be more careful with firearms in the home.

"I believe that something positive will come out of this -- that another family won't go through the heartbreak of this family," he said.

Most Video Game Guns Don't Look as Lifelife

Ashe did not know the specific Wii game the child played or the manufacturer of the video game controller. Nintendo did not immediately provide a comment to ABCNews.com.

Michael Fahey, a reporter for the video game blog Kotaku, said lifelike gun controllers, like the one found by police at the Cronberger home, are very rare.

"It's not one that's generally on sale," he said. "You can't generally find it on sale in the U.S. because no one wants to sell a realistic-looking gun controller to children."

After searching online, Fahey said he came across a video game controller that he thinks could be the same one owned by the Cronbergers.

Manufactured by the HAIHONGCHANG Electronics Company in China, the WiiAuto Pistol, he said, is available for sale on various Web sites, such as eBay. The company did not immediately respond to a request for comment from ABCNews.com.

Fahey said he wasn't even aware of the video game controller until Tuesday.

"It surprised me, really, to see a gun that realistic being used for [the Wii]," he said.

Gun-Control Advocate: Gun-Related Accidents Happens 'All too Often'

Most toy guns marketed for kids' video games in the United States are brightly-colored or white, to distinguish them from real guns. But he said he didn't think there was a way for Nintendo to regulate what overseas third-party manufacturers create for the Wii console. Nintendo might not have even known the realistic-looking gun existed, he said.

He also said he doubted there were many shooting video games meant for young children. Those that do target kids, such as Nerf N-Strike, try to design toy guns that don't resemble the real thing.

Gun-control advocates say it's one more reminder of the dangers of guns in the home.

"The fact that there are things like this Wii toy that look like guns, make it all the more important for the adults to keep the guns away from the children," said Paul Helmke, president of the Brady Campaign to Prevent Gun Violence. "Keep it locked up, keep it secure, or don't have it at all."

Though not all gun accidents end as tragically as Cheyenne's, he said this kind of incident happens "all too often." In the United States, he said, a gun in the home is 21 times more likely to injure a family member than protect the home from intruders.

"It shows once again that guns are not toys," he said. "Guns should not be left around where a child could get to them."