Residents of Tuakau in the north Waikato have been evacuated after a large amount of an unknown chemical entered drains near the town's water treatment plant, with authorities noting the substance's origin is not yet known. Fire and Emergency New Zealand, seeking specialist input from the Queensland Fire Department, is coordinating the response as Waikato District Council and Watercare plan to flush the drains safely. Residents in Kowhai Street and Matipo Drive were told to stay indoors with doors and windows closed, while others were asked to stay away from the area. Police and St John provided scene support and medical staff as evacuations continue. The incident, reported around 4pm, is developing as officials work to identify the chemical and secure the area.