A 7-year-old girl is the only survivor of a boating accident that killed two family members during a fishing trip.

The girl was on board the boat with her grandfather and great-grandfather when it capsized on Sunday, August 18, in the LaSalle Lake State Fish and Wildlife Area in Illinois, according to a news release from the Illinois Conservation Police.

Clarence B. Royster, 80, Clarence B. Royster III, 53, and the 7-year-old girl were on a 17-foot Crestliner fishing boat when it began to capsize. The LaSalle County Coroner publicly identified the men on Tuesday, Aug. 20. According to the news release, police said neither man was wearing a life jacket, but the child was.

The incident occurred at the 2,000-acre man-made LaSalle Lake, located near Marseilles, Illinois, about 80 miles southwest of Chicago.

Shortly after noon, authorities received a 911 call about a “boater in distress” at the lake. When police arrived, they found the young girl on the shore with park visitors. The visitors assisted the child and helped her contact her mother and grandmother, the news release said.

Authorities were assisted in the search for the two men by additional police officers and rescue workers from numerous agencies. The men’s bodies were recovered at 7:45 p.m. on Sunday evening. The LaSalle County Coroner pronounced them dead at the scene, the press release states.

According to police, it is not yet clear what caused the boat to capsize. The LaSalle County Coroner’s Office and the Illinois State Conservation Police are currently investigating the incident.

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A representative for the Illinois Conservation Police did not immediately respond to PEOPLE’s request for further information Tuesday.