Armed police have descended on a rural township in Auckland's west

Police say they're conducting an operation at an address in Waitakere township.

Bethells Rd is currently closed.

Local residents are being allowed access to their homes through the police cordon.

Police say they can't provide further details.

Waitakere Primary School says it has been told by police that the incident that has been unfolding is contained.

A worker at Silver Star Farm says he's heard a helicopter flying around the area on-and-off for about an hour.

Photos posted to social media show armed police blocking a stretch of road.

One woman on Facebook said her teenaged son is home alone and has locked all of the windows and doors.