The offenders left the property in a car and are thought to have travelled towards the Thornbury township.
"It is believed possible that a fourth person was involved who was driving the vehicle.
"The offenders, prior to leaving, have attempted to search the house although at this point it is not known if anything has been stolen.
"The male victim received fractures to his neck along with a laceration to his head and was treated at Southland Hospital and has been discharged.
"Both he and his partner along with their child who was also home at the time have been traumatised by this serious, cowardly and unprovoked attack."
Police today conducted a scene examination. There are currently 10 officers working on the investigation.
Police want to hear from anyone who may have information on the attack. Call the Invercargill Police station on (03) 211 0500 or phone Crimestoppers anonymously on 0800 555 111.