He said she managed to escape but he caught her and beat her again about the face with a closed hand before he tied her up again.
Mr King described the attack as "cowardly", brutal and unprovoked.
"The courageous victim managed to break free but was then rebound again. The offender took an undisclosed amount of cash in notes and coins from the club's bar. He then fled the scene and ran onto Hobsonville Road.
"It's not known if a car was used from this point. The offender did not speak either during the assault or the robbery."
The attacker was in the RSA for only about 5-10 minutes and the woman was discovered by a cleaner at about 9.30am.
The victim has been discharged from hospital but has been left severely traumatised with serious bruising to her face.
Mr King worked on the inquiry into the Mt Wellington RSA murders 10 years ago and said that while there was no link between the robberies, his thoughts were with the victims of that event as they commenced that investigation.
The scene is still cordoned off and police are now studying CCTV footage.
The attacker is described as a Maori man in his 30s, with a stocky build. He was wearing a black hoodie, black jeans and a white and green mask.
Police want to hear from anyone who has observed any suspicious behaviour in the area where the RSA is located. Members of the public will have been walking or driving on Hobsonville Road near the RSA prior to 8.00am.
Anniversary of attack
The robbery comes ten years to the day after the Mt Wellington RSA murders.
Returned Services Association president Don McIver said it was devastating to have an assault coming on the anniversary.
He was "shattered" at news of the attack.
"It brings back terrible memories of what happened in the past. The coincidence of it being on the anniversary of that terrible event is horrible."
Mr McIver said the RSA would do all it could to care for the woman assaulted during the robbery.
"All we can say is how sorry we are she was involved in this.
"We would have hoped people would respect the place of the RSA in society."
Ten years ago today, William Bell stormed into the Mt Wellington-Panmure Returned Services Association premises and shot four people in the chest before bludgeoning them with the butt of his shotgun.
Club president Bill Absolum, club member Wayne Johnson and cleaner Mary Hobson died. Susan Couch, who worked part time doing the club's accounts, survived.
Bell left the mother-of-one for dead with broken arms and severe head injuries that caused a stroke. She lost about 80 per cent of her blood and ambulance officers later said she came as close to dying as she could get.
Bell was convicted of three murders and one charge of attempted murder and is serving a life sentence at Paremoremo - New Zealand's toughest prison.
He is not eligible for parole until 2031.
Darnell Tupe, who was Bell's getaway driver but took off early, was sentenced to 12 years' jail for manslaughter and aggravated robbery.
A memorial service was held at the RSA today, attended by victims' families, Sensible Sentencing Trust director Garth McVicar and the Crown Solicitor for Auckland, Simon Moore SC, who was the prosecutor for the trial.
