Click on the KTLA source cite... You’ll get your answer....
I did click on it, but could not find that info. Was she wearing shoes or not?
I did see a link to this story, though:
“Nail gun sold at Walmart recalled over ‘involuntary discharge’”
Imagine how much fun Freepers could have with that one!
The only additional information the article provided was that she had to have her leg amputated and that Walmart admitted that she stepped on the nail in the store. How it all happened is not revealed.