Police attended an incident on Miro St in Whanganui yesterday afternoon.
A cordon was put up between Ruapehu St and Kowhai St while officers were stationed at each corner.
Armed offenders squad officers and police dogs appeared to be concentrating on a property in the middle of the block.
The cordon was lifted just before 4pm.
A police spokesperson yesterday afternoon said the operation was still under way, so no details could yet be provided.