Parents have started arriving to take children home after three people were taken to hospital - two in a serious condition - affected by a gas leak at an early childhood centre on Auckland’s North Shore.

Emergency services are at the Caterpillars to Butterflies Early Childhood Centre on Coronation Rd in Hillcrest after a call at 11.54am.

A staff member told the Herald no children had been harmed by the incident. She said teachers had been made unwell.

A police spokesperson said enquiries were underway into the exact circumstances surrounding the incident that saw three taken to hospital.

Children have remained at the centre throughout the ordeal.

One parent told the Herald the centre had been calling parents to notify them of the incident. At 2pm parents had started arriving to pick up their children and take them home early.

A St John spokesperson said one person in moderate condition and two people in serious condition were being transported to North Shore Hospital.

Firefighters outside the Caterpillars to Butterflies Early Chilhood Centre responding to a gas leak which has seen teachers taken to hospital for treatment.

They said St John responded with two rapid response units, four ambulances, and one operations manager.

A Fire and Emergency spokesperson said it was responding to the leak with two firetrucks.

Police at the Caterpillars to Butterflies early learning centre on Auckland's North Shore after a gas leak that saw three staff taken to hospital.

Nearly two hours after the incident all St John vehicles had left the scene but four police cars remained.