Counties Manukau police Detective Sergeant Glenn Wilkinson described the incident as a "violent and terrifying attack on a defenceless elderly couple".
"We're appealing for anyone who may have seen either of the offenders or their car in the John Street area yesterday afternoon to contact us as soon as possible.
"It's possible there could be up to three offenders involved."
A white vehicle was seen parked in the victim's driveway during the assault, described as similar to a Toyota Corolla.
The man who knocked on the door prior to the assault was described as a Pacific Island male aged in his 30s, with long black hair, a beard and wearing a red and white t-shirt.
One of the men who allegedly invaded the house were described as having light brown skin and a chubby build.
The couple had been discharged from hospital and were recovering with family, Mr Wilkinson said.
Anyone with information is asked to call the Counties Manukau crime squad on 027 497 4912 or Crimestoppers anonymously on 0800 555 111.