He saw the male driver get out of his vehicle with what appeared to be moderate injuries so told him to sit down and wait for the ambulance while he went to check the woman and child.
However, instead of waiting, the offending driver jumped into the good Samaritan's vehicle, and was last seen heading towards Paihia.
Yesterday police were still looking for the driver and the vehicle, a silver-coloured Nissan Pulsar station wagon, registration DPK966.
The good news was that the woman and the child were treated at the scene by St John Ambulance medics and did not require further treatment.
''The car seat this young boy was sitting in has certainly done its job,'' Le Comte said.
Two crews from Kawakawa Fire Brigade also responded to the crash.
Call police on 105 or Crimestoppers, anonymously, on 0800 555 111 with any information about the driver or the missing car.