Three family members were shot to death while camping in a state park in eastern Iowa Friday, and the suspected gunman died of a self-inflicted gunshot wound, police said.

Officers responded to reports of the shooting at the Maquoketa Caves State Park Campground before 6:30 a.m. Friday, the Iowa Division of Criminal Investigation said in a statement. Officers found three people fatally shot in a tent at the campground, division assistant director Mitch Mortvedt said.

The victims from Cedar Falls, Iowa — identified by the Iowa Department of Public Safety as Tyler Schmidt, 42; Sarah Schmidt, 42; and Lulu Schmidt, 6 — were found in their tent early Friday at the Maquoketa Caves State Park Campground, about 180 miles (290 kilometers) east of Des Moines.

Investigators provided no motive for the attack.

Officials immediately evacuated everyone from the park, a children’s summer camp on the grounds, and the campground. Once the evacuation was complete, the only registered camper not accounted for was 23-year-old Anthony Sherwin, Mortvedt said.

“He was known to be armed. That of course heightened our awareness as well,” Mortvedt said. Iowa allows people with permits to carry firearms virtually anywhere in the state. Officials did not say if Sherwin had a permit.

Using a plane to help search the area, law enforcement later found Sherwin dead from a self-inflicted gunshot wound in a wooded area of the park. Sherwin came from Nebraska, and investigators don’t believe he had any prior relationship with the victims, Mortvedt said.

Mortvedt said he could not say whether Sherwin had a criminal record. A search of online court records in Nebraska and Iowa did not produce any record of prior criminal behavior.

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 park, which remained closed Friday, is about 50 miles (80 kilometers) east of Cedar Rapids.

AP UPDATE: The couple leaves behind a nine-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.

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.

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.