Two people have been choppered to hospital after a boat capsized on the Eyre River, west of Kaiapoi.
Emergency services were called to the shores of the river, which flows south-east into the Waimakariri River, shortly before 3pm after the boat carrying the group of four toppled.
Two of the four-strong group were injured in the incident, one seriously and one moderately.
A rescue chopper has flown the pair to Christchurch Hospital, a St John spokeswoman says.