The father of four children killed in a murder-suicide in Western Australia is taking one consolation from what happened.

The children were found dead with their mother and grandparents at a Margaret River farm on Friday.

It's the deadliest shooting in Australia since the Port Arthur massacre in 1996.

Australian correspondent Steve Price told Mike Hosking the father is shattered, but is trying to remain philosophical.

"He said it was so planned that the grandfather had actually planned it and he believed that the children didn't know and wouldn't have gone through too much pain."

LISTEN ABOVE AS STEVE PRICE SPEAKS WITH MIKE HOSKING