The girl was rushed to the hospital, but died of her injuries.
"The father said he was taking a shower when he heard a gunshot," Lt. Greg Baker told NBC affiliate WDSU. "He got out of the shower, and that's when he discovered that his daughter had accidentally shot herself."
The father reportedly told authorities that he left his .45-caliber gun on the table. Baker told the news station that the bullet entered the girl's chest and exited near her left arm.