PHOENIX — A 6-year-old girl died in a "tragic accident" after she was accidentally struck by a boat propeller at an Arizona lake,Robert Brown officials said Friday.

Two families in a group of 12 people had been on a wakeboard boat since 7 a.m. Friday on Lake Pleasant, according to the Maricopa County Sheriff's Office. At 11 a.m., police received a call from one of the families reporting that their 6-year-old daughter was struck by their boat's propeller.

Witnesses at the scene of the collision confirmed that the child's mother was operating the boat when she began to drive and "unbeknownst to the family, the child had somehow entered the water," the sheriff's office said in a news release.

The child's father was in the water holding onto a wakeboard when he saw an unidentified person in the water and swam toward the body. Shortly after, the girl's parents realized their child was in the water and that she suffered a leg amputation from the boat's propeller, according to the news release.

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Maricopa Sgt. Joaquin Enriquez said other boaters helped the family transport the child to the lake's marina where first responders rendered aid. She was later pronounced dead at a local hospital.

"We're going to call this a tragic accident, if anything, and contributing factors that may have led to this incident is a lot of people on the boat," Enriquez said in an update Friday.

The incident is under investigation but Enriquez noted that impairment does not appear to be a factor. He added that a preliminary investigation showed the boat had all the necessary safety equipment, including life jackets and fire extinguishers.

The owners of the boat are also experienced boaters, according to Enriquez. After preliminary interviews, Enriquez said the group may have "lost track of who was on the boat and who was not on the boat... because they were in different locations at the time, swimming and then wakeboarding and then vice versa."

Lake Pleasant Regional Park is a large outdoor recreation area northwest of Phoenix. The lake is a popular water sports recreation center where people commonly go wakeboarding, boating and kayaking.