Investigators believe a grandfather gunned down his wife, daughter, her four children and then himself in what authorities say is the deadliest mass shooting in Australia in 22 years.

The New York Post reports that three guns recovered from the scene belong to 61-year-old Peter Miles, who owned the remote farmstead where the bodies were found on Friday.

Aside from Miles, the victims are his 58-year-old wife, Cynda Miles; their daughter, 35-year-old Katrina Miles; and her four autistic children: 13-year-old Taye, 12-year-old Rylan, 10-year-old Ayre and 8-year-old and Kayden.

Western Australia Police Commissioner Chris Dawson declined to comment on whether the killings were a murder-suicide, but he said at least six of the family members were victims of homicide.

“I will confirm all seven deceased suffered gunshot wounds,” Dawson told reporters at a press conference. “We are treating this as a matter in which clearly six persons are the subject of a homicide crime scene.”

As for the seventh person, Dawson said: “There is a seventh person deceased. It’s far too premature for me to come to any conclusive statement about that.”

The Weekend Australian, citing sources with knowledge of the investigation, reports that authorities suspect Peter Miles was the gunman.

Dawson said police responded to an emergency call from a male at the farm at 5:15 a.m. Friday.

“We know where the call was made from. We know whose phone it was made from. I’ve listened to the message. I’ve been briefed by the homicide officers. While we’ve come to some preliminary conclusions … I’m not going to speculate as to the chronology,” Dawson said.

According to Perth Now, police found Peter Miles slouched over on a chair with a gun between his legs and injuries to his head; his wife also was found in the home.

Their daughter and her children were discovered in a retooled shed, where they reportedly lived and where the kids were home schooled.

A neighbor told Seven News Perth that Peter Miles was “acting strange” the day before the bodies were found.

“[He was] just not someone who I would have thought was keen to find a new client or customer,” Richard Dossor told the news organization.

Dossor said he had just talked with Miles about watching his property for a time while he was gone.

“He didn’t seem enthusiastic, if you know what I mean.”

Miles ran a business maintaining farms and used to teach agriculture at a high school.

The family had its share of adversity. According to Perth Now, Miles’ son killed himself 15 years ago and his daughter had a troubled relationship with her children’s father.

Relatives of the family said they were struggling to comprehend the killings.

“We are stunned and still trying to understand how this could happen. … We thank the community for their support and ask that our privacy is respected as we grieve,” the family said in a written statement.

Police said the father of the children is not considered a suspect.

Meanwhile, locals shared their dismay and sorrow over the slayings. Felicity Haynes, who lives near the Miles farm, characterized the family as “lovely people.”

“They were a very socially-aware family – doing their best to create a safe community – and that is why it is so shocking to think that could be destroyed so quickly,” Haynes old the Australian Broadcasting Corporation.

The killings are the worst mass murder in Australia since a gunman killed 35 people and injured 23 others at a Tasmania restaurant in 1996.

After the 1996 incident, the Australian government prohibited automatic and semiautomatic guns.

[Feature image: Katrina Miles and children/Facebook]