UPDATED 2.25pm: A teacher at Whangaparaoa College says it's back to business as usual after this afternoon's scare.

She said the kids will be having a "long lunch" before going back into the classroom.

The teacher says everything went smoothly when the school went into lockdown.

She says there was an element of excitement and nervousness among the children.

The school was in lockdown for about 45 minutes.

Police locate teenager at centre of scare

UPDATED 1.12pm: Police have caught the 18-year-old who triggered the lockdown of two schools north of Auckland.

Those schools are Whangaparaoa College and Whangaparaoa Primary School. Police are on site.

It follows reports the man - who is believed to be suffering from a mental health condition is there - and is possibly armed with a knife.

The 18 year old isn't a current student at the school.

Several other schools in the area have gone into voluntary lockdown too.

A large number of police units are in the area - both on foot and in cars.

A Police Eagle helicopter is also circling overhead.

Parents of the children are asked to refrain from calling 111 at this stage.