Four children and three adults have been found dead at a home in rural Western Australia.

Detectives have described the incident at a farm northwest of the holiday town of Margaret River as a "horrific tragedy".

Western Australia Police Commissioner Chris Dawson said police were called to the property at 5.15am on Friday.

Two of the adults were found outside and the other five victims were inside the home in Osmington, 20km northeast of Margaret River in the famous wine region.

Police found two firearms and Commissioner Dawson confirmed some of the bodies had gunshot wounds.

He said the "male person" who had called the police had some connection to the property.

Margaret River in Western Australia | Image: Google Earth

The incident has taken its toll on first responders, he added.

"This devastating tragedy will no doubt have a lasting impact on the families concerned, the whole community and, in particular, the local communities in our southwest," he said.

"Homicide Squad detectives from Perth are assisting local police in investigating the circumstances surrounding this tragedy.

"They will be supported by other specialist police units.

"A police chaplain is in attendance to provide support to all persons, officers and others that are impacted by what has happened."

He said police will be at the farm for "several days at least".

The commissioner was unable to confirm the ages of the children as their next of kin are still being notified.