The men were not wearing helmets or any protective gear, he said.
St John Whanganui territory manager John Stretton said the two men, both 27, were on the motorcycle when they crashed, and suffered "serious injuries".
Upon finding the two unconscious men, Mr Rogers ran back inside for his cellphone and called the ambulance, then returned to look after the men.
He said one regained consciousness at one point and tried to sit up.
Paramedics rushed them to hospital in a critical condition, both status one.
Conditions range from zero to five, with zero meaning dead.
A police spokeswoman confirmed on Thursday one man was in Whanganui Hospital in a status three condition, while the other man had been transferred to Wellington, still status one.