The victim's father-in-law, Terry Rutledge, told The Associated Press that Veronica Rutledge "was a beautiful, young, loving mother."

"She was not the least bit irresponsible," Terry Rutledge said. "She was taken much too soon."

The woman's husband was not in the store when the shooting happened at about 10:20 a.m. Tuesday. Miller said the man arrived shortly after the shooting. All the children were taken to a relative's house.

The shooting occurred in the Wal-Mart in Hayden, Idaho, a town about 40 miles northeast of Spokane, Washington. The store closed for the rest of the day.

Brooke Buchanan, a spokeswoman for Wal-Mart, said in a statement the shooting was a "very sad and tragic accident."

"We are working closely with the local sheriff's department while they investigate what happened," Buchanan said.

There do not appear to be reliable national statistics about the number of accidental fatalities involving children handling guns.

In neighboring Washington state, a 3-year-old boy was seriously injured in November when he accidentally shot himself in the face in a home in Lake Stevens, about 30 miles north of Seattle.

In April, a 2-year-old boy apparently shot and killed his 11-year-old sister while they and their siblings played with a gun inside a Philadelphia home. Authorities said the gun was believed to have been brought into the home by the mother's boyfriend.

Hayden is a politically conservative town of about 9,000 people just north of Coeur d'Alene, in Idaho's northern panhandle.

Idaho lawmakers passed legislation earlier this year allowing concealed weapons on the state's public college and university campuses.

Despite facing opposition from all eight of the state's university college presidents, lawmakers sided with gun rights advocates who said the law would better uphold the Second Amendment.

Under the law, gun holders are barred from bringing their weapons into dormitories or buildings that hold more than 1,000 people, such as stadiums or concert halls.