National Manager Road Policing Superintendent Carey Griffiths said:
"Often the same factors appear following an investigation such as speed, alcohol and drugs, failing to wear restraints, dangerous and careless driving behaviours and high-risk drivers and distractions," he said.
He asked motorists to slow down, ensure everyone in the vehicle wears their seatbelt, drive responsibly and be alert to other road users.
The New Zealand Transport Agency said it was always looking at ways to develop a safer roading system, and this week's road toll was a reminder of how much more work was needed.
"We are looking at what's happening over the course of years and decades, and have got a pretty sustained effort working with police and others to prevent these kind of tragedies from happening," NZTA spokesman Andy Knackstedt said.
"When you have a week like this it's terrible, and it's a reminder really of how much work there is to be done."
There did not appear to be any trend in this week's crashes, Motoring Affairs General Manager for the New Zealand Automobile Association Mike Noon said.
"They have all been quite different. It is a reminder to be so careful and cautious.
"The advice from the AA would be to keep the speed down and moderate your driving to the conditions of the road, that also means if the road has heavy traffic," Mr Noon said.
Fatal crashes this week
Yesterday
• 17-year-old youth dies when his car rolls in wet weather near Te Kuiti. He was not wearing a seatbelt and did not hold a current driver's licence.
Wednesday
• Two people killed after a truck travelling over the Crown Range near Queenstown rolls and hits a stone wall.
• An elderly woman dies after a head-on collision south of Wanganui.
Tuesday
• 27-year-old woman dies after her car and a fuel tanker collide head-on on State Highway 3, north of Midhirst.
Monday
• 13-year-old girl dies in a crash on a notorious stretch of road on State Highway 1, near Otaki, north of Wellington.
• Man in his late 20s dies when his motorcycle and a truck collided in Mangakino.
• Truck driver dies in a crash between the Dominion Rd on-ramp and the Hillsborough Rd off-ramp