(AP) — A Cedar Falls couple and their 6-year-old daughter were fatally shot while camping at an Iowa state park in an apparently random attack by a man from Nebraska, who later turned the gun on himself, authorities said.

The couple leaves behind a 9-year-old son, according to the Cedar Falls mayor. It was not immediately clear Saturday if the boy was with his family at the time of the attack at the Maquoketa Caves State Park Campground.

The Iowa Department of Public Safety identified the victims as Tyler Schmidt, 42; his 42-year-old wife, Sarah Schmidt; and their 6-year-old daughter, Lula Schmidt. Their bodies were found in their tent early Friday at the campground, about 180 miles east of Des Moines.

Authorities said the suspected gunman, 23-year-old Anthony Sherwin, was found dead in a wooded area of the park with a self-inflicted gunshot wound.

Mitch Mortvedt, assistant director of the Department of Public Safety’s division of criminal investigation, told The Associated Press on Saturday that the motive for the attack was still unknown.

“We don’t know what led up to this, what precipitated it,” he said, adding that so far, “the investigation has not revealed any early interaction between the Schmidt family and him.”

Cedar Falls Mayor Rob Green, who said he is a neighbor of the Schmidts, posted on Facebook on Friday that the couple’s 9-year-old son, Arlo, “survived the attack, and is safe.” The post did not say whether Arlo was in the tent or at the campsite when the shootings happened, and Green told the AP he did not have those details. Authorities would not immediately confirm the information in the mayor’s post or make any comment about the boy.

Sarah Schmidt worked at the Cedar Falls Public Library, which was closed Saturday after news of her death.

“Like many of you just hearing the news, I’m devastated,” Green wrote on Facebook. “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 7/26.

“Their 9-year-old son Arlo survived the attack, and is safe,” Green wrote. “I’ve notified neighbors, and for those of you just learning about this through this post, I am so sorry.” He said he would share upcoming details about services and memorials.

By Saturday afternoon, more than $40,000 had flowed into a GoFundMe page created for Arlo. The page, which says it was organized by a cousin, Beth Shapiro, said: “Arlo is a strong boy, surrounded by family and friends who are supporting him as best we can.” The page says the fund will help Arlo now, and help fund his future education.

The killings prompted the evacuation of the park and campground, including a children’s summer camp. After the evacuations, Sherwin was the only person unaccounted for, Mortvedt said.

He said that during the course of the investigation, authorities learned Sherwin was armed and “that of course heightened our awareness.” Iowa allows people with permits to carry firearms virtually anywhere in the state. Officials did not say if Sherwin had a permit and provided no information about the firearm that was used to kill the Schmidts.

The Des Moines Register reported that Sherwin came from La Vista, Nebraska. La Vista Police Chief Bob Lausten told the newspaper that Sherwin had lived in an apartment complex with his parents and that he had no history of criminal conduct.

Autopsies on Sherwin and the victims were scheduled to be performed over the weekend, Mortvedt said, and more information would likely be released based on those findings.

The state park and campground were closed until further notice. The Department of Natural Resources said in an email to the AP that campers with reservations through Thursday were given refunds. All of the campers who were at the park but not associated with the shooting have been able to retrieve their belongings, the DNR said.