Two people have complained of dizziness after inhaling a harmful gas leaking from a freezer at a supermarket in Paraparaumu.
Central Fire Service shift manager Murray Dunbar said emergency services were notified of a "refrigerant leak" at Countdown supermarket in the Coastlands Shopping Centre about 3.30pm.
Six people overcome from gas inhalation were treated by Wellington Free Ambulance staff at the scene and two patients complaining of dizziness were taken to Wellington Hospital in moderate condition.
A number of fire trucks and a specialist hazardous materials vehicle were at the scene.
Fire staff have since handed over to refrigeration contractors.