Police are looking for a man seen leaving a house in Remuera, Auckland, in a "distressed" state and possibly holding a knife.
Officers were called to a property on Seascape Rd, about 8.30am, after a report of concern for a person's mental health state.
"A man at the address appears to have left in a distressed state and there are concerns for his mental health. It's believed he may be in possession of a knife."
Police said just after 10.30am that authorities were still in the area working to find him and have advised nearby schools as a precautionary measure.
The man is described as being about 173cm tall, of thin build and with blonde hair. He is wearing black track pants and a purple T-shirt.
Auckland's Meadowbank School was placed in lockdown as a precaution.
Several police officers and vehicles are outside the Remuera primary school.
A neighbour said she had seen police officers in the area early this morning, but did not know the exact circumstances of the lockdown.
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A notice on the school's website was posted later on, telling parents that the situation was now under control.
"We have come out of lockdown and all students, staff and persons on-site are safely accounted for. Everyone did extremely well and responded to instructions.
"A notice will be going out to parents [and] caregivers tonight to provide some more information about our emergency lockdown procedures."
Police are warning the public that the man should not be approached and anyone who sees him is urged to contact authorities immediately on 111.