Three people suffered serious injuries and one is in a moderate condition after a plane bounced off the edge of a runway at a Marlborough airfield.
The injured include a teenage girl, and a woman in her 40s.
Emergency were called to the incident at a remote Kekerengu airstrip, north of Clarence about 11.30am.
The plane plunged over the edge of the runway while attempting to land and came to rest about 40m down the hillside.
Four people were on the privately owned and operated Cessna 185 F and one had to be cut out from the plane by the Fire Service, police said.
A woman in her 40s and a teenage girl - both in a serious condition - were flown to Christchurch Hospital by the Life Flight Westpac Rescue Helicopter, while two other patients were flown to the same hospital in a separate chopper.
According to Nelson Marlbourgh Rescue Helicopter, all four had spinal and ambdominal injuries.
The pilot was landing on a farm airstrip when it ran off the side of the strip, a Civil Aviation Authority spokesman said.
"The impact of the accident caused the undercarriage to collapse."
Emergency services gained access to the remote airstrip by quadbikes.
Maritime New Zealand tweeted an emergency beacon was set off at 11.33am.
Beacon alert received by RCCNZ at 11.33 am from light plane crashed near Clarence. Police leading response.— Maritime New Zealand (@MaritimeNZ) January 19, 2017
The signal had been picked by the national rescue co-ordination centre.