Five people, including twin 4-year-old girls, were winched to safety last night after their four-wheel-drive became stuck in the Waimakariri River.
David O'Connor, who was driving the Toyota Surf, told Newshub the dramatic rescue unfolded after he tried rescuing a friend.
Along with his partner, O'Connor ventured into the Canterbury Plains river to help a mate who became stuck with his three children in their jet boat.
Soon after rescuing the stranded family, the Toyota 4WD cut out and got stuck about midway across the river.
"We all clambered on to the roof of this thing and tried to be as patient as we could," he told Newshub.
Temperatures in the area, near Eyrewell Forest, had nearly reached freezing point at 1C when the rescue mission took place.
A short time later, the Canterbury Rescue helicopter arrived, battling strong winds and darkness before lowering the winch.
The river flow wasn't high, but the conditions were far from perfect.
The helicopter crew battled winds of up to 60 knots (111km/h) and the dark. Equipped with night vision goggles, they got to work.
Helicopter crewman Wayne Ledgerwood guided pilot George McInnes while paramedic Tatsu Kawasaki was lowered to the stranded group.
"The group stayed very calm on the roof of the vehicle and worked well with our team, which made things easier," Ledgerwood told Newshub.
The main concern for the group was hypothermia, a police spokesman told the Herald last night, but no one was injured in the rescue.
Before the rescue helicopter arrived, another vehicle had tried to navigate through the river to winch the stricken car without success.