100m evacuation zone in place after chemical explosion at Ruawai College pool

The explosion happened at Ruawai College, Dargaville. Photo / Annette Lambly

A person has been injured and a 100m emergency evacuation zone is in place after a chemical explosion at a school pool in Northland.

Ruawai College has been isolated after a person tending the pool added the wrong product, causing a volatile reaction.

Those inside a nearby home were forced to evacuate as the reaction continued for more than an hour.

The accident happened just after 11.35am today.

Four fire crews were at the school trying to neutralise the reaction.

Northern Fire Service communication shift manager Jaron Phillips said when the chemicals were mixed they caused an explosion and it was "still going off".

A person had inadvertently inhaled poisonous fumes and was being treated by ambulance officers for minor injuries.

Firefighters were wearing fully protective chemical splash suits and breathing apparatus as they dealt with the hazardous substances.

He said as a precaution the area surrounding the school had been isolated.

The emergency zone stretched 100m from Ruawai College as chemicals continued to react and give off gas.