US police have charged a young man with murdering his parents and three teenage sisters at their home near a village in rural Iowa at the weekend.
Iowa authorities expect to have the suspect returned shortly
Shawn Bentler, 22, allegedly shot Michael and Sandra Bentler, 53 and 47, and Sheena, 17, Shelby, 15, and Shayne, 14, at their house outside Bonaparte.
He was arrested 60 miles (100km) away in Illinois on an unrelated charge.
The Bentlers were an affluent family, owning an elevator and lumber company which served most of south-east Iowa.
Shawn Bentler faces five counts of first-degree murder, the sheriff's office in Van Buren County, where Bonaparte is located, announced.
He is being held in Quincy, Illinois, since his arrest on Saturday for possession of drug paraphernalia.
Local newspaper The Des Moines Register quoted officials as saying it was one of the worst mass murders in Iowa history.
'Just the worst'
The sheriff's office says it received an emergency call at 0338 on Saturday from Shayne Bentler who told the dispatcher her brother was "going to do something".
Police have been keeping people away from the crime scene
A gunshot followed in the background, then someone screaming "Shawn, no!" before the line went dead.
A second emergency call came in at the same time from the mobile phone of Sandra Bentler. The call went unanswered.
Shawn Bentler could be returned to Iowa as early as Monday, said Jim Saunders, spokesman for the Iowa department of public safety.
Investigators have not offered a motive for the killings, he added.
The Des Moines Register says the Bentler house is located on a hill outside Bonaparte overlooking the Des Moines river.
Bill Vickers, who lives a half-mile from the house, said the Bentlers were "good people, fine people, every one of them".
"It's a real bad deal," he added. "It's just the worst. It's the kind of thing you hear happening in Des Moines or Chicago. Not Bonaparte. But it did."