The offender then fled the scene in couple's 2004 brown Toyota Vitz, registration number HYT799.
Both victims were admitted to Auckland Hospital with a number of injuries, and it was suspected both had broken jaws, the police statement said.
St John spokesman Robbie Walker said one ambulance was dispatched to the house and transported the couple to Auckland City Hospital.
A hospital spokesperson said they were treated in the Emergency Department and discharged.
Police have described the offender as in his 20s, 185cm tall with a solid build and of Polynesian descent.
He had short black hair, was clean shaven, and was wearing a black baseball cap backwards, black trousers and a black singlet.
Police have asked anyone with information to call either 111, 09 571 2800, or Crime Stoppers on 0800 555 111.