The family of Marli Hamblin confirmed she died Sunday from injuries suffered during Friday's accident.
According to police, Hamblin was sunbathing in her family's driveway in Syracuse, Utah on Friday, when her sister, unaware of Hamblin's presence, backed a truck out of the garage, crushing Hamblin. Police say Hamblin was listening to music with headphones in her ears and did not hear the truck.
"The driver wasn't paying attention, obviously didn't think there would be anyone in the driveway, and just backed out of the driveway," Officer Erin Behm of the Syracuse Police Department told local reporters.
Hamblin was airlifted to Ogden Regional Medical Center, where she was in a coma until her death on Sunday.
"Always be aware, tragedies, accidents–unfortunately, they happen far too often. However, if you're in a big truck and you look behind you, you might not be able to see directly behind you, and I think that that's what happened here: It was just an accident."
Hamblin's older sister is not facing any criminal charges.
"[Marli's older sister]'s having a very difficult time, beating herself up," cousin Ron Hamblin said.
"All we can do is encourage her you know, it's just an accident, it can happen to anybody at any given time."