Updated 5.21pm: A young boy is in hospital in a critical condition after being hit by a car in the Auckland suburb of Mount Eden this morning.

Police at the scene say the accident is devastating - especially as it comes on the second day of Road Safety Awareness Week.

Inspector Chris Tate of police northern communications said the child ran into oncoming traffic on Mt Eden Rd about 11.30am.

"The adult went to grab the child. The child was hit by oncoming traffic and the adult was also hit," he said.

A St John spokeswoman said the child was taken to Starship Hospital in a serious condition and the woman to Auckland City Hospital.

Mr Tate said the woman was in a moderate condition.

The driver of the car is helping police with their investigation into the incident.

Police say the driver stopped immediately, and her car is being examined as they investigate the incident.

Witnesses at a church playgroup nearby have also been giving statements to police.