A tow truck driver who police believe is connected to the rape of numerous women has been arrested after police raided three houses in Sydney's north-west this morning.

Gregory John Richardson was taken to Ryde police station as part of an investigation by the Child Abuse and Sex Crimes Squad into 12 historic sexual assaults on women and children across almost 30 years.

Police swooped on a home at Epping at 7am, where the 51-year-old was arrested. He was led to the police car still wearing his pyjamas.

Gregory John Richardson is accused of sexually assaulting 12 women and children over a thirty year period. Picture: 9NEWS (9NEWS)

The 51-year-old allegedly assaulted children as young as 14. Picture: NSW Police (Supplied)

Officers later carried out search warrants at properties in Ryde and Berrilee.

Between 1989 and 2007, police claim Mr Richardson sexually assaulted 12 victims, with a total of 20 offences.

The victims range in age from 14 to 40.

Two assaults reportedly took place in Beecroft in 1989. Four were reported in Cheltenham between 1994 and 2004.

Three allegedly occurred in Hornsby in 2007.

The suspect has been taken back to Ryde police station. Picture: NSW Police (Supplied)

Police conducted early raids on three properties in Sydney's north-west this morning. Picture: NSW Police (Supplied)

Three allegedly occurred in the surrounding suburbs of Wahroonga, Epping and Macquarie Park between 2004 and 2007.

As Mr Richardson was led away in handcuffs, police phoned his alleged victims to deliver the news.

"It was mixed emotions, some of them very relieved, some were grateful of the progress and sadly some of them very emotional," said Detective Superintendent John Kerlate.

"Some of them have put this way behind them, the phone call today reignited some of those initial feelings, so it was an emotional time for them."

Neighbours have said the man went away on trips interstate with his tow truck. Picture: 9NEWS (Nine)

Police say it was a mix of witnesses accounts, evidence gathered at the crime scenes, and similarities between the crimes that led to today's arrest.

DNA testing will now be crucial to proving their case.

"It was like a jigsaw puzzle, without knowing what the end picture looked like," said Detective Superintendent Kerlate.

Neighbour David Swinbourne told 9NEWS the man lived at the home with his mother, who has since died.

He said most people in the street had nothing to do with the suspect, apart from seeing him drive away in his tow truck every morning.

"It does come as a shock," Mr Swinbourne said.

Officers swept on the home at around 7am. Picture: 9NEWS (Nine)

"We just did not know."

Another neighbour Kylie Funk said she saw the suspect regularly and "he always seemed fine".

"We always help him out, feed his dog when he goes away, we have a key to his house," she said.

The sexual assaults date back to 1989. Picture: 9NEWS (Nine)

"I've only been here for four years, and he's had one partner. She seemed like a lovely lady when I was pregnant about three years ago.

Ms Funk said the man was recently taking his tow truck on longer trips interstate.