Three people including two young children are dead and a man is in custody after police were called to a “particularly violent crime scene” that has stunned the local community.

The bodies were discovered in different rooms of the property on Raymond Ave in the southwestern Sydney suburb of Campbelltown following a Triple-0 call from the residence just before 8pm on Monday.

They are yet to be formally identified but police said they are a woman in her mid-40s and two children aged under 10.

“Whilst I can’t give you specific information in 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,” Acting Superintendent Michael Moroney said.

A 48-year-old man, who police previously reported as aged 47, was taken into custody and is now at the Campbelltown Police Station where he will be formally interviewed.

Police are reportedly treating it as a potential domestic violence incident.

“Whilst we’ve confirmed (the man’s) identity, the link to the three people inside has not been established at this stage,” Moroney said.

“However, we believe they are all known to each other.”

Police are not currently searching for anyone else and believe “there are no outstanding offenders”.

It is understood the man in custody was the person to call Triple-0, requesting emergency services attend the home.

“Police have located a number of items inside the premises which would be of interest in regards to the injuries sustained by those people,” he said.

“Until that crime scene is processed, I can’t confirm the exact cause of deaths of those people at this time.”

A woman and two children have been found dead in Campelltown.A woman and two children have been found dead in Campelltown. Credit: 7NEWS Acting Superintendent Michael Moroney.Acting Superintendent Michael Moroney. Credit: 7NEWS

The inspector said the man in custody was not previously known to police.

An investigation by Campbelltown detectives and the homicide squad is now underway, with a section of the street now cordoned off.

Locals told 7NEWS they were stunned by the tragic news.

“Growing up in Campbelltown, you don’t expect stuff like that to happen,” Bailey Proctor said.

“Hearing especially that it’s kids, it’s really shocking and it’s a real eye-opener that things can happen so close to home, you know?”

No charges have been laid.

Anyone with information should contact police.