Australian rock musician and anti-violence campaigner Angry Anderson has returned to Sydney following the death of his youngest son.

Emergency services were called to the corner of Pavilion Street and Bridge Road at Queenscliff just after 6am yesterday following reports of an assault.

A 20-year-old man was allegedly found beating former friend Liam Anderson, 26, who was unconscious with serious head injuries.

Liam Anderson with his rock icon father. (Facebook)

The younger man was arrested at the scene, after officers used pepper spray to restrain him.

Anderson was rushed by paramedics to Freshwater Beach but died before he could be loaded into a waiting air ambulance.

Northern Beaches crime manager Detective Inspector Michael Boutouridis said the alleged offender did not co-operate with officers initially.

Angry Anderson returning home this evening. (9NEWS)

The rocker was in Perth on tour at the time of his son's shocking death. (9NEWS)

"The man we have in custody was violent and it took a number of police officers to subdue and arrest him," he said.

"Capsicum spray was used and significant force to arrest him.

"I don't know the circumstances leading to them being at the reserve this morning.

"It is a quiet area. The assault was brutal. It was quite a bloody scene."

Liam Anderson is believed to be the 26-year-old killed in a "bloody assault" this morning. (Facebook)

Rose Tattoo singer Angry Anderson with his youngest son Liam. (Facebook)

Neighbours told 9NEWS they heard moaning sounds coming from Pavilion Reserve just after 5.30am.

"We started to hear aggressive moaning and it just kept getting louder and louder," Kim Luker told 9NEWS.

"Then at 6.10am it was really loud and then all of a sudden it just stopped."

The man died en route to hospital. (9news)

Another man was arrested at the scene and has been taken to Manly Police Station. (9news)

Angry Anderson is on tour with his current band in Perth, and was woken by eldest son Galen who broke the news.

The 71-year-old rocker is now returning home to be with his children and friends.

Liam Anderson's mother spoke from her home in northern New South Wales, telling 9NEWS her son, an aspiring hip-hop rapper, wrote lyrics to express himself.

Detective Inspector Michael Boutouridis addresses the media outside Manly Police Station. (9news)

Emergency services were called to Queenscliff just after 6am following reports of an assault. (9news)

The devastated mother said she's thinking about tomorrow when she tries to call him, knowing he won't pick up.

A hand-written note taped to a bin outside the Rose Tattoo lead singer's Beacon Hill home requested privacy.

“We will not be answering any media questions. Thank you for your understanding,” the note read.

The note left outside Angry Anderson's home. (9NEWS)

The 20-year-old remains at Manly Police Station where he was questioned by police today.

Detectives have said they plan to charge the 20-year-old with murder.

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