The woman told sheriff's deputies she was standing on the passenger side of the pickup when the gun discharged. She walked away from the vehicle toward Hepplers Pond Road, first noticing a pain on the left side of her stomach. The woman said she pulled up her shirt and saw she was bleeding but kept walking. She then noticed a pain in her upper right chest and pulled her shirt down to see a bleeding cut. Moments later she collapsed.
The woman's 22-year-old boyfriend who had followed her called a friend, who called for an ambulance, the sheriff's office said.
The woman was taken to a local hospital and then transported by medical helicopter to Utah Valley Regional Medical Center in Provo.
Paramedics and a doctor who treated the woman told police the bullet appears to have entered the left side of the woman's body and exited just above her right breast. Deputies said the bullet passed through rear of the truck's cab.
The shooting was ruled accidental.