"Peter didn't snap. He's thought this through. I think he's been thinking this through for a long time," he said.

"All these kids died peacefully in their beds. The [police officer] that went through, he said they looked all peaceful. How the hell Peter did that I still can't figure out, but if someone did it ... he did a good job, he did a really good job."

Mr Cockman said his former father-in-law was "an awesome man, before this all blew up. He was like my best friend. I still love who he was, but his mental attitude... There are some people you just don't want to get on the wrong side of. That's Peter and Cynda.''

Seven people were found shot dead on a 30-acre hobby farm in Osmington, 270km south of Perth, in the early hours of Friday morning.

They were identified as Peter Miles and his wife Cynda, 61 and 58, their daughter Katrina, 35, and her four children Taye, 13, Rylan, 12, Ayre, 10, and Kayden Cockman, 8.

Earlier, Mr Cockman visited an idyllic bush chapel to lay flowers in memory of his family.

West Australian Premier Mark McGowan has met with grieving residents of the Margaret River community.

He said the deaths were “one of the worst tragedies WA has ever seen” and “something all of us feel very keenly and very deeply”.

“I expect the grieving process will go on for many years for that family,” he said.

He thanked everyone who was assisting in the aftermath of the shootings and offered his commiserations to those who had “endured the unendurable”.

The incident would be “talked about for many years to come” and all West Australians were thinking of the family, he said.

Mr McGowan said Australia served as an example for the rest of world “that you have to have very careful and strict gun laws”.

He said in this case it appears the guns were licensed.

“It was a farming property. There is not much else I can see from the outside could have been done,” he said.

The West Australian government would await the coroner’s inquiry, he said.

Police Commissioner Chris Dawson said he did not intend to release the triple-zero call made by a man from the property where the murder-suicide took place.

He said there was “not much I would add” to the comments he had already made but forensic procedures were continuing alongside investigative and analytical work.

“I’m not going to put a timeframe on that,” Mr Dawson said.

He offered his thanks to the police officers who first attended this "difficult and challenging job".

On Saturday, Commissioner Dawson confirmed three long-arm firearms were recovered at the property, all of which were licensed to Peter Miles.

“I wish to strongly emphasise police do not believe any other person is involved with these crimes. Police are not searching for any other suspect,” Commissioner Dawson said.

Support is available for those who may be distressed by phoning Lifeline 13 11 14; Mensline 1300 789 978; Kids Helpline 1800 551 800; beyondblue 1300 224 636.