Police, including members of the Armed Offenders Squad, were called to the property in Coast Rd at 3.20pm today after a man was shot and critically injured.
The Otago Daily Times understands he was shot in the head.
St John was alerted to the incident at 3.35pm and sent one ambulance, a rapid response unit, a St John manager and one helicopter to the scene.
A man on a stretcher was seen being loaded into a helicopter about 4.45pm. He has been taken to Christchurch Hospital, police said tonight.
Police arrested the suspect soon after the shooting.
An ODT reporter witnessed a man in handcuffs who had been arrested on the side of State Highway 1, near Waitati. He was then put into a police car by a member of the AOS just after 4pm.
There were at least four police vehicles at the scene.
"Police are still working to establish the circumstances, however it is believe the two men were known to each other."
Det Insp Harvey said police were not looking for anyone else in relation to the incident.
A scene guard remained at the property tonight while the examination continued.
He appealed for anyone with information about the shooting to contact police on 105 and quote file number 211015/4195.
A Coast Rd resident told the ODT they had heard about the incident from their daughter who had told them to stay inside.
Another resident said they could hear a helicopter overhead.
