The death is currently being treated as "unexplained". An autopsy will take place tomorrow.
The injured man was taken to Middlemore Hospital and is in a critical condition this afternoon, police said.
A scene examination is under way this afternoon at the McNally Rd property and a scene guard will remain in place overnight.
A St John spokeswoman said one ambulance, one rapid response unit and one incident manager was sent to the scene.
St John was alerted to the Pukekohe incident at 9.06am.
• Police ask that anyone who may have information that may assist their inquiries to contact Counties Manukau Crime Squad on 09 261 1321.