Neighbours reported hearing ambulance and fire services rushing to the property where the couple lived.
"The husband got killed and the wife is fighting for her life in hospital. They are local people," said one man, who did not wish to be named.
The property is owned by Brian Steere, who does not live at the address.
A Christchurch-based family member of Mr Steere's confirmed the accident had taken place and that a couple had been living at the property and working on the farm.