Emergency services are attending a water rescue incident in central Auckland.
St John said a patient was in a serious condition and was being taken to hospital.
A police spokeswoman said a woman had been found in the water at Quay St shortly before 4pm.
Members of the public helped the woman out of the water and onto a nearby boat.
She was treated by paramedics at Princes Wharf before being taken to hospital.
Police were talking to witnesses to ascertain what had happened.
Auckland Transport spokesman Mark Hannan couldn't confirm reports the woman had fallen from a ferry.
Princes Wharf is opposite the ferry terminal.