The children had spent time in Auckland, Waikato and Tauranga visiting family members between 23 and 26 March.
There's no link to travel abroad and it is believed the children caught the highly contagious disease locally, National Public Health Service clinical director Dr William Rainger said.
He said being vaccinated against measles is crucial, and anyone with symptoms should stay home and seek advice before visiting a doctor.
Symptoms of measles can start about a week to 18 days after a person has been exposed to the virus, Te Whatu Ora advised on its website.
A fever, cough, runny nose, and sore red eyes are among the most common symptoms.
It can be followed by a red or dark pink rash on the face or behind the ears about three days after the first symptoms. White spots can also appear in the mouth.
The spots, while not itchy, can be blotchy and close to one another. This can last for more than a week.
It can leave children in bed for about five days but still unable to attend school for a couple of weeks.
