Police later said six people were recovered, with one person located deceased and one taken to hospital in a critical condition by the Westpac Rescue Helicopter.
Hato Hone St John said they were notified of an incident at Dorie at 1.02pm and sent two ambulances, an operations manager, two rapid response vehicles and a helicopter.
“One person has been airlifted to Christchurch Hospital in a critical condition,” a spokesperson said.
Fire and Emergency New Zealand also helped with the response, along with a member of the public in a private vessel.
The mouth of the Rakaia River is about 80km south of Christchurch. It is a popular spot with salmon and trout anglers, as well as boaties and 4WD and ATV enthusiasts.
– More to come