A man smashed a car windscreen with his fist to help free a child and a man trapped inside a car that was submerged in a Nelson creek on Saturday.
Police have named the woman who died in the crash as Janice Anne Fa'avae, 68, and say it was her husband and two-year-old grandson who were rescued.
They say the car crossed QE2 Drive in Nelson and crashed into Saltwater Creek just after midday.
A Tasman Police District spokesperson, Barbara Dunn, says four members of the public jumped into the creek to rescue them, with the man who smashed the window having sustained injuries. Ms Dunn says that although the car was fully submerged, they put their lives at risk to get the car's occupants out.
Police say the man is recovering in Nelson Hospital while the toddler, has been flown to Starship Hospital in Auckland.
A serious crash investigation is under way.