Ruapehu Alpine Rescue Organisation members were left to treat the man while the helicopter was then sent to attend the 69-year-old man with chest pains.
He was flown to Taupo Hospital in an unstable condition and then transferred to Waikato Hospital, where he is recovering in the Cardiac Care Unit.
The helicopter returned to Mt Ngauruhoe to pick up the 32-year-old man, but they were then called to the summit of the mountain where a 27-year-old-woman had a serious knee injury and was unable to walk.
Low cloud made access by helicopter difficult with both patients having to be moved to locations where they could be loaded into the helicopter while it hovered close to the mountain.
The two patients were taken off Mt Ngauruhoe and flown to Taupo Hospital.
"It's pretty uncommon to have so many (incidents) in one day," said Constable Conrad Smith.
National Park police praised the efforts of the volunteer rescuers who helped the three injured people in difficult conditions.