Ms Walsh said she counted up to eight emergency service staff working on two patients on the ground in the paddock.
"They tried adrenaline, they had a defibrillator but it didn't seem to make any difference," she said.
"From what we could see, three were with the baby and four with the woman. Then they stopped working on the baby and started resuscitating her," she said.
Ms Walsh said the stretch of road was dangerous and had been especially slippery last night.
"It's a dodgy road, very country, very dangerous."
Northern Fire Communications shift manager Megan Ruru said the car had ended up in a paddock after hitting a powerpole. She said it appeared a small child was trapped in the car.
The child was removed to an ambulance for medical treatment but had subsequently died, Ms Ruru said.
Police closed the road for several hours while dealing with the situation.
St John Western Bay of Plenty territory manager Ross Clarke said the young child was a pre-schooler. The woman did not require medical treatment, he said.
The death comes two days after a man was killed while walking along State Highway 2 at Te Puna.
Grant Coley, 59, died when he stepped out in front of traffic travelling north. He was struck by a truck.
On January 24, Auckland man Santhosh Kumar Cherukuri died in a crash on SH2 at Pahoia.
