Police said the fire was not being treated as suspicious and appears to be an accident.
Fire and Emergency New Zealand shift manager Jordan Barnett said fire services were called to Mount Maunganui at 6:45pm.
A person had reported a car fire that was "well-involved".
Barnett said a well-involved fire meant it was "not a small fire - the car had been well-involved in fire".
He said fire services arrived at 6:48pm, and was not certain how long it took to extinguish.
A St John ambulance spokeswoman confirmed they were called to the fire at 6:42pm.
She said one ambulance and one rapid response unit responded to the scene and treated three patients. Two were in a moderate condition and one was in a minor condition.
None of the patients required transportation.