She said the woman was in a stable condition at Auckland City Hospital.
Senior Sergeant Grant Miller said such crashes happen in an instant but the repercussions for all those involved are lasting.
"Our Serious Crash Unit is investigating the circumstances leading up to the crash and our thoughts are with the families involved," he said.
The driver of the crash vehicle stopped immediately and she has since given a statement to officers.
"The car has been removed from Mt Eden Rd and will be examined as part of the investigation."
Mr Miller said witnesses who were visibly upset outside a church playgroup had also spoken with officers at the scene.
Attending officers described the scene as devastating, particularly in light of the fact it is day two of the United Nations Global Road Safety Week which focuses on promoting increased safety awareness around our most vulnerable road users.