Two girls remain in hospital with their father by their side after a road crash claimed their mother's life.

The younger girl, aged 5, is in a critical condition in Auckland's Starship Children's Hospital, where both were flown on Friday night after the tragic smash. Her 7-year-old sister was in a stable condition, a hospital spokeswoman said.

Neighbours are caring for the Waimauku family's pets, including a dog badly injured in the crash.

Police said they were being helped in their investigation by the driver of the other car, which collided at the intersection of Muriwai and Hamilton Rds about 7.30pm.

The death of the girls' mother took the annual road toll to 299 yesterday, 30 more than during the same period last year. "It's sad," said Superintendent Carey Grifiths, the national manager of road policing. "We get to this time of year and we should be celebrating with our families and opening our presents.

"For too many families Christmas is going to be a time of remembrance for lost loved ones, and it shouldn't be that way."

Waimauku resident Mike Morgan was one of the first people at the scene. He said it was "pretty traumatic for everyone".

The young girls were still conscious after the crash but dazed as paramedics tended to them, he said.

Their mother is understood to have been pronounced dead at the scene. "I don't think [the girls] were aware of what was going on at the time," Morgan said. "One had been thrown from the car."

He has lived on the road for nine years and said it was notorious for drivers who flouted the rules. "Those corners are not forgiving. We've lobbied to have a sign put on that corner ... It's a shockingly dangerous piece of road."

Griffiths said another fatal crash at Tokoroa on Friday afternoon was suspected to have been the result of a driver's medical condition.

- APNZ