According to Lt. Trent Colledge with the Orem Police Department, the ball struck the girl, who was about 18 meters away, in the back of the head at the base of her neck.
On impact with the club, the father's golf ball traveled in an unintended direction, and struck his child in the back of the neck, the lieutenant said. She was then flown to Primary Children's Medical Center in Salt Lake City in extremely critical condition.
The incident is being investigated as a tragic accident, Colledge said, adding that police are not pursuing charges. Kellen and his wife, Talysa Hill, are also parents to twin boys.
"She loved doing it and had a good time with it all", Mr Smith said.
Camera IconAria Hill (front) with her family.
Aria went golfing with her dad often, her uncle, David Smith, said. Aria was the sassiest girl in the world. "That was something that was really important to them".
Steven Marett, the head golf professional at the golf course, said that while he'd occasionally seen people get hit with golf balls at the course before, he had never heard of anybody being killed by a ball or even seriously injured. "Aria brought contagious joy and light to every room or place she entered, and is dearly loved by so many because of the love she shared so freely and effortlessly".