The operation is understood to be related to an incident which occurred in the area last night but which was reported this morning.
Police say around 4.13am today a car pulled out in front of a police vehicle and stopped in the middle of the road on State Highway 11 near the Puketona Junction with State Highway 10.
Before the officer could get out of the patrol car, two men got out of their car and aimed guns at him, Northland district commander Superintendent Tony Hill said.
The officer immediately retreated but one shot was fired at the vehicle which shattered the windscreen.
The officer was not harmed and quickly left the scene and called for backup.