A horrific neighbourhood dispute involving a chainsaw has left one man with a partially severed arm and another without a finger.

Mark Jorgensen, 29, is undergoing emergency surgery to his right arm, after an altercation with his neighbour in Minto, near Campbelltown. Paramedics say they believed it would have to be amputated.

His father Laurie told The Telegraph the brawl with the next door family started earlier in the afternoon, over complaints to do with loud music and reckless driving in the street.

It is alleged that when Mark approached the neighbours to sort out their differences, Troy Thornton, 26, came at him with a chainsaw.

Troy's mother Wendy confirmed her son did wield the chainsaw, but said he grabbed it to defend himself.

"They (the Jorgensen family) had machetes and bats, and we had nothing so Troy grabbed the chainsaw," she said.

Both families agreed to ongoing differences, but Mr Jorgensen said sorting it out with a chainsaw was extreme.

"Fists maybe, but this is just over the top," he said.

Mr Thorton's family said he was staying at the house comforting his sister Nicole who recently lost her partner when his runabout overturned on the Nepean River.

Peter Reinhart was reported missing after he went for a late night spin in his new tinnie. His body was found a few days later.

The couple had a four-week-old baby son named Jackson.

"Troy lives in Queensland but he's been here looking after Nicole," his mother said.

Outside both Fenton Cl houses today, pools of blood remain splattered across the driveways and road.

Detectives have seized mobile phone footage of the attack and are investigating it.

Police had responded to Fenton Crescent, Minto, following reports a person armed with a chainsaw had entered a house.

Detective Chief Inspector Mark Brett described the incident as horrific.

"A chainsaw is a serious weapon which inflicts pretty brutal injuries," he said.

He said police were called to the street for a fight between two neighbours, which escalated when weapons were wielded.

"It's very disturbing... A chainsaw and a samurai sword are serious weapons," Det Ch Brett said.

No charges have been laid.

He said it was too early to say who would be charged.

"We still have 12 more statements to take," he said.

Forensic specialists last night set up a crime scene while detectives interviewed others at the home.