One person is in a serious condition after a jetboat rolled on the Waimakariri River.
Emergency services were called to the river just before 10.30AM on Sunday.
A St John Ambulance spokeswoman said two helicopters were sent to the scene and staff treated two patients.
One person is in a serious condition and one is in a minor condition.
Both have been transported to Christchurch hospital via helicopter.
A police spokeswoman said they received the report but were not required to attend the scene.