SINGAPORE: A man charged with killing a woman his partner and her two boys had allegedly planned the murders for months after reading a news article about a similar incident in Perth.

Police will allege MD Shomon Ahamed stabbed the woman, 46, and two children, aged 12 and four, to death at their Campbelltown home on Monday night before calling triple-0 about 8pm.

It is understood the 47-year-old man was a carer for the two boys. Sources said it is understood the older boy had severe learning disabilities.

A neighbour in the street said she had met the mother and two children about two years ago, the only interaction she had with them.

“They kept to themselves, they were very withdrawn,” Amanda Wasilewski said.

“No sort of friendly waves like the neighbours around here.”

Ms Wasilewski said it was “absolutely confronting and overwhelming” to know what was allegedly taking place just a few houses away while she had been relaxing in front of the fireplace.

“I’ve got no words, honestly.”

Another neighbour, who declined to give her name, came to lay fresh cut roses near the home and say a prayer for the alleged victims.

She said the incident was “too close to home” as she wiped away tears.

“This is just terrible,” she said. “I’m feeling for these children.

“Their friends, they’ve got to come to school to find out that their little mate’s not going to come to school today.”

Two women who appeared to be loved ones of the family arrived in the street about 12.30pm on Tuesday.

They approached detectives before having a short conversation and breaking out in loud wails.

Police later moved them out of sight of media after attempting to console them.

Emergency services were called to the Campbelltown home about 7.50pm Monday after receiving a triple-0 call from the property.

Police found the bodies of a 46-year-old woman and two young boys, aged four and 12, inside the house.

Police will allege Ahamed had carefully planned to murder the woman and two boys, aged 12 and 4, since reading the article, the Daily Telegraph reported.

According to court documents seen by NewsWire, police allege the murders took place sometime between 9am and 7.55pm on Monday.

Mr Ahamed was arrested at the scene and has since been charged with three counts of murder.

He did not appear in Campbelltown Local Court when his matter was briefly mentioned on Tuesday morning.

He did not apply for bail, and it was formally refused. He will next appear in court on July 15.

Outside court, Mr Ahamed’s lawyer Jawad Hosain said his client was “pretty distressed” and “distraught”.

“It’s obviously a very tragic set of circumstances at the moment … for the (alleged) victim, the community, and the family,” he said.

Acting Superintendent Michael Moroney said on Tuesday that the house was “described as a very traumatic scene, a very horrific scene”.

Inspector Moroney said the woman and two children were found in separate areas of the house, describing it as a “particularly violent crime scene”

“I can’t give you specific information regards to how they passed – what I can tell you is all three persons sustained significant injuries and it was a particularly violent crime scene,” he said.

Local federal MP Mike Freelander on Tuesday paid tribute to the emergency service crews and first responders who attended the scene.

“I know this is devastating to our entire community. We will get through this but we will get through it by offering support to each other,” Dr Freelander said.

“I want to offer my thanks and support to all the emergency services and first responder crews … this is a tragedy,” he said.

“This is a tragedy for our community. This is a tragedy for Australia”.

Inspector Moroney said a “number of items” were seized from the scene, but did not specify what they were.

He said the items “would be of interest in regards to the injuries sustained to those people”.

Inspector Moroney said the man was not known to police.

“We’re not aware of any interactions with this male before and certainly not aware of any domestic-related incidents previously reported to police,” he said.

“But I can reassure the public that domestic violence is the number one priority for NSW Police and we will continue to prioritise (alleged) DV offenders.”

Residents in the street told Sunrise they were horrified by the incident.

“Well, growing up in Campbelltown, you didn’t don’t expect stuff like that to happen,” one local said.

“So hearing especially that it’s kids, it’s really shocking.

“And it’s a real eye-opener that things can (happen) close to home.”

The otherwise quiet suburban street was cordoned off on Tuesday morning as forensic detectives continued combing the scene.