The mother of the three year told police the girl got her hands on a gun and shot herself.
The mom called emergency personnel but their attempts to resuscitate the child were futile and she was pronounced dead.
Investigators say the gun belongs to the girl’s father and they are investigating further before they call it an accident.
It’s the first shooting in the park since 1978 and the first of a child since 1938, partly because having or firing a gun in Yellowstone is illegal.
Carrying a weapon into any National Park was not allowed until 2009. That’s when Oklahoma Senator Tom Coburn put forth an amendment to a credit card reform bill that allowed guns in the parks.
That bill passed 90-5 and it was signed into law by President Obama.
Park workers point out to the Associated Press "given the 3 million visitors we see here every year, there thankfully are very few fatalities reported in the park."
The spokesman went on to say the leading cause of death in Yellowstone is heart attacks.