A heroic builder has described the moment he heard a woman scream for help as she was stabbed in the chest.

A builder has described the moment he heard a woman scream for help and shout out “he’s gonna kill me” before she was stabbed in the chest in Sydney’s east.

Peter Haramis intervened during the violent altercation, then helped police identify the accused man’s vehicle so he could be taken into custody, and assisted the injured woman until paramedics arrived to rush her to hospital.

The 45-year-old woman was stabbed outside a property on Weonga Rd in Dover Heights about 12.15pm on Monday.

Mr Haramis, from Trident Design and Construction, told NCA NewsWire he had just eaten his lunch and was about to resume working when he heard the woman scream: “Help! Help!”

“I started walking up the hill and then it was becoming more panicked, it was more of a scream,” he said.

“She was just screaming: ‘Help me! Help! He’s gonna kill me!’

“Then I started running up the hill and as I got to that front staircase, she was on her knees and he was over the top of her, so his chest was on her back.

“He sort of looked at me and he froze for a second and I thought, I’m gonna have to run at him here. I don’t know what’s going to happen.”

But then the woman managed to get the knife off the man and threw it past Mr Haramis on the grass.

“I picked up the knife ... he started walking towards me,” he said.

“She jumped up, ran in the house, locked the door.

“He was just walking towards me saying: ‘Give me the knife.’

“I said: ‘No, you’re not getting it.’

“Then the guy just calmly turns around and starts walking up the hill to his car.”

Mr Haramis immediately called for police and an ambulance, then followed the man up to his car to get a description of the vehicle.

“I wasn’t going to let him get away,” he said.

“I just let them know the plates and the colour and where it was going.”

Then he returned to the property to check on the woman while still on the phone with the operator.

“She showed me the wound and it was just it was just like a two or three centimetre stab wound that was in her chest,” he said.

“But she wasn’t leaking blood or anything. On the knife I was holding it was about four to five centimetres of blood on it, so I think it went in but it hit her ribs.

“I think that might have been what would have saved her.”

Mr Haramis said the entire ordeal was actually “pretty calm”.

He admitted he was the type of person who would usually intervene in an altercation.

“Not because I enjoy conflict, just because I know how to handle it. I know what to do,” he said.

“I don’t know, I just thought I have to do something.”

But Mr Haramis does not believe he is a hero.

“I just hope she makes a full recovery,” he said.

Paramedics stabilised the woman, then rushed her to St Vincent’s Hospital where she remains in a critical but stable condition.

“This was a very traumatic scene to arrive at with a significant, life threatening stab wound,” NSW Ambulance Inspection Giles Buchanan said.

“Paramedics administered IV fluids, stemmed the bleeding and provided pain relief to stabilise the patient.

“Stabbing wounds are generally confronting incidents and this patient has suffered a very serious injury.”

Police said a 46-year-old man was arrested a short time later on Campbell Pde in Bondi.

He has been taken to Waverley Police Station and is “assisting detectives with inquiries”.

“The man and woman are known to one another,” police said in a statement.

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