Police, fire and the hazardous materials unit are at a house on Clayton Rd, with part of the street cordoned off.
About six police cars, three fire appliances and the hazardous materials control unit (HazMat) are at the address, near the intersection with Spencer St.
A Rotorua Daily Post reporter at the scene said workers wearing white overalls were outside the house.
She said about 50m of Clayton Rd had been cordoned off and blocked to traffic and pedestrians.
Police had escorted at least two people from the house, she said.
