The 55-year-old was found dead at 2am on Friday at a Somerton Park home.

His son, 26, is in police custody and his wife is in hospital with non life-threatening injuries. It's understood his daughter is overseas on holidays.

Police said Walsh suffered "multiple stab wounds", while his wife suffered a "leg injury".

The suspected murder weapon, a knife, has been found at the scene.

"There's been an argument, I can't tell you anything about the argument … but as a result of that both Mr Walsh and his wife received a wound and the wound ultimately caused Mr Walsh's death," a South Australia detective told reporters at the scene on Friday.

"A knife was used in the attack and that has been found at the scene. At this stage, we won't say what sort of knife."

Walsh's son left the scene and was found soon after by police in the suburb of Glenelg East, the detective said.

"His son was located at First Avenue, Glenelg East, and arrested for murder and detained for a psychiatric assessment," he said.

The detective said Walsh's son lived at the Somerton Park house with his parents.

"He must have been out or elsewhere and returned there about 2 o'clock," he said.

"Somebody from the house called triple-0 and asked for an ambulance and the ambulance contacted police.

"What transpired I actually can't tell you. I'm sure we will establish exactly what happened and what led to this tragic event."

The detective said the incident was tragic, regardless of Walsh's high profile.

"It's not even just that he's a high profile [coach] ... it's just terrible that a family has been torn apart. It's just one of the worst things you could image could happen to you ... the pain and suffering of the family is no different," he said.

The AFL has yet to comment.

The Crows are scheduled to host Geelong at Adelaide Oval on Sunday. That match is now in doubt. Shocked Adelaide Crows players were arriving at Adelaide Oval.

In  February, in an interview with Fairfax Media's chief football writer Caroline Wilson, Walsh spoke about the impact of grief in the aftermath of a training accident which left player Brent Reilly with a fractured skull.

"Part of the old Phil Walsh might have screamed at Brent Reilly to get up," said the new Adelaide coach at the time. "Sitting in that hospital, I really wondered if the worst happened whether I would be able to make those same physical demands on the team.

"In the end, after he came through the operation, I told the guys: 'Let's just get through the week. I won't coach and I won't make demands on you and if you don't feel you can train, then don't.

"What I've learnt from working with large groups is that we all deal with grief differently. We needed to find out who was grieving and get them the relief they needed."

Nathan Brown, former Richmond player and Nine Network commentator, said the death was shocking and would impact many AFL clubs.

"I'm shocked," Brown has told the Nine Network.

"At the moment beside myself that a lot of players are going to wake up today and be on their way to training and find out this news.

"He played for Collingwood, he played for Brisbane. He's been at West Coast, he's been at half the AFL clubs. This is going to touch so many people."

A statement from South Australian police, released at 7.16am said: "Police can confirm that the man murdered at Somerton Park in the early hours of the morning is Phil Walsh, coach of the Adelaide Crows.

"Just after 2am, Police and ambulance crews were called to a house in Bungey Avenue after a domestic dispute.

"Ambulance crews treated a seriously injured 55-year-old man at the home but sadly he died at the scene. The man's son, aged 26, has been arrested but no charge has yet been laid.

"The deceased's wife sustained non life threatening injuries during the incident and is currently receiving treatment in hospital.

"Sturt CIB and Major Crime Detectives remain at the scene and investigations continue."