Four children were removed from the suspected meth lab in Taradale last night.
Two Child, Youth and Family (CYF) social workers who visited the property earlier in the day alerted emergency services after they became ill later that afternoon, police said.
"Police searched the house yesterday evening and while no meth lab was operating, police found a number of items of interest."
A Ministry of Social Development spokesperson said Child, Youth and Family staff have been treated for possible exposure to dangerous chemicals.
"They are being supported and are fine. We will ensure they can access further treatment if needed. We cannot comment further as a Police investigation is underway."
The Elliott St property in Taradale was cordoned off overnight and police have now resumed their examination this morning.
Police said the Fire Service was called to decontaminate emergency services staff and the house occupants, including the children who were taken into CYF care overnight.
Two people were arrested as a result of the raid and are being interviewed today.
Armed Offenders Squad members and emergency service workers in hazardous materials suits converged on Elliott St at about 6pm.
Neighbours watched on as emergency service workers were decontaminated.
One neighbour spoke of her surprise at the raid.
"I had no idea what was going on, I just came home with my hot chips and saw these men in [hazmat] suits all over the place."
She said the young parents that lived at the house were always very quiet and respectful.
"They are never noisy or throw parties."
She often saw children playing outside.
"As a mother and grandmother, I'm really feeling for the children right now, it's not their fault and they'll have no idea what's going on."
She was told by police that the children were taken away. "It's very sad," she said.
When asked if children were present, district deployment officer for Eastern District Police Dan Foley said he could not rule out the possibility of others living at the address.
"It appears to be a clan lab," Mr Foley said.
He said products used to manufacture methamphetamine are extremely dangerous and not just for children.
"However, the chemicals are far more harmful to children as their organs are still developing."
