(CNN) — Two parents and their 6-year-old daughter were found dead at an Iowa campground Friday, and a 4th person died of a self-inflicted gunshot wound, in what authorities are investigating as a triple homicide.

Cedar Falls residents Tyler Schmidt and Sarah Schmidt, both 42, and their daughter Lula, 6, were identified as the three victims whose bodies were found Friday morning at a campground at Maquoketa Caves State Park, the Iowa Department of Public Safety said.

Officers with the Jackson County Sheriff’s Office and Division of Criminal Investigation also found a camper was unaccounted for and discovered the body of Anthony Orlando Sherwin, 23, west of the park, the department said. Sherwin, who is described as the suspect, appeared to have a self-inflicted gunshot wound, the department said.

Cedar Falls Mayor Rob Green said in a Facebook post Sarah Schmidt was his neighbor and worked for the city’s public library.

“Like many of you just hearing the news, I’m devastated,” Green wrote. “I knew Sarah well, and she & her family were regular walkers here in the Sartori Park neighborhood. I was working with her this week on a public library tech presentation for (July 26).”

He said the Schmidts’ 9-year-old son survived the attack and is safe.

“Details will be forthcoming about services and other memorials, and I will ensure the community knows about this,” he added. “Please offer some extra grace to the Schmidts’ many friends, neighbors, and coworkers as we try to process this horrible tragedy. The Cedar Falls Library will be closed tomorrow for the sake of the staff who loved and worked with Sarah.”

The deaths led to an evacuation of the state park, located about 60 miles east of Cedar Rapids. The park is closed to the public until further notice, police said.

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