A reduced 4km/h speed threshold would be strictly enforced through until 6am next Monday, Mr Brown said.
Associate Transport Minister Michael Woodhouse said the toll proved a reminder for motorists to take care on the road.
"It is important that we remain vigilant on the roads all year long. Already this year more than 80 families have lost loved ones due to road crashes, and many more are dealing with the consequences of serious injuries.''
The first fatality was on Thursday at 5.20pm when a 44-year-old female driver from Twizel died following a crash on the Fairlie-Tekapo Road in South Canterbury.
Her vehicle was travelling along State Highway 8 from Fairlie towards Tekapo and appeared to have lost control, left the road and hit a tree, police said.
Speed, the vehicle's poor condition and bad weather were contributing factors, police said.
The driver was not believed to have been wearing a seatbelt.
Shortly afterwards, 40-year-old Alofaifo Afaese, of Helensville, died instantly when the Mitsubishi Pajero in which she was travelling with her husband and two of their children was involved in a head-on collision with a Subaru on State Highway 16 west of Kumeu.
On Friday about 3.15am, Alan Hammond, 80, of Ashburton was struck by a vehicle on the Hinds-Rangitata Highway, about 5km south of Hinds, South Canterbury.
He died as a result his injuries.
Speed and wet conditions are believed to be factors in a road crash that cost a 27-year-old Auckland woman her life about 7.20am yesterday.
Lysette Michelle Brown, from Whenuapai, was driving north on the Coatesville-Riverhead Highway northwest of Auckland when her vehicle collided with a truck travelling in the opposite direction.
The collision occurred near a bend in wet conditions, and the impact seriously damaged the side of Ms Brown's vehicle.