A six-year-old girl and her parents were shot dead while camping in Iowa, police said.
The US State Department of Public Safety said the bodies of Sarah and Tyler Schmidt, both 42, and their daughter Lula were found in their tent at Maquoketa Caves State Park. .
A relative said the couple’s nine-year-old son, who was also on the trip, survived.
Authorities said the motive for the attack was unclear.
Suspected shooter Anthony Sherwin, 23, who was also staying at the campsite, was found dead in a wooded area of the park with a self-inflicted gunshot wound.
Mitch Mortvedt, deputy director of the Department of Public Safety’s Criminal Investigations Division, said: “We don’t know what led to this, what precipitated it.
“Investigation revealed no early interaction between the Schmidt family and him.”
Adam Morehouse, Sarah Schmidt’s brother, said the family had no connection to Sherwin.
“It was a completely random act,” Mr Morehouse said.
“He was just an individual who decided that morning to pick a tent and go in there and carry out the mission of what he wanted to do.”
Cedar Falls Mayor Rob Green, who said he is a neighbor of the Schmidts, posted on Facebook on Friday that the couple’s nine-year-old son, Arlo, “survived the attack and is safe.”
The post didn’t say whether Arlo was in the tent or even at the campsite when the shooting happened, and the mayor said he didn’t have those details.
Mr Morehouse confirmed Arlo was on a camping trip with the family, but said he did not know exactly where the boy was at the time of the shooting or how it happened .
“He’s with his family and he’s fine, but I haven’t had any interaction with him,” Mr Morehouse said.
“As far as I know, he was not physically injured.”
The murders prompted the evacuation of the park and campground, including a children’s summer camp.
After the evacuations, the suspected shooter was the only person missing, Mortvedt said.
Officials did not say if he had a firearms license and provided no information about the weapon used to kill the Schmidts.
Iowa allows licensed individuals to carry firearms virtually anywhere in the state.