Use of a mobile phone and lack of seatbelt are contributing factors in the Te Puna crash that killed mother-of-two Tracey O'Brien, according to police preliminary results.

The 26-year-old was travelling towards Tauranga with her two children on Saturday when her car crossed the centreline colliding head-on with a north-bound peoplemover on State Highway 2 at Loop Road.

Tracey O'Brien was killed and her two children injured when her car crashed with another vehicle on State Highway 2 on Saturday.

Tracey died at the scene and her two children son Phoenix, 4, and three-year-old daughter Faith suffered serious injuries. The children are both in a stable condition at Starship Hospital.

Tracey will be farewelled at a funeral service The Omokoroa Community Church, Hamurana Road on Monday.

Her funeral notice released this afternoon describes Tracey as a devoted mummy of Phoenix and Faith and much loved daughter of Peter and Vera.

"Loving sister of Timothy, Abigail, and Richard ( U.K.). Treasured family member of the Ruddell Family and of her family in the U.K," the notice went on to say.

The service will be followed by a private cremation.In lieu of flowers, the family ask people to consider donations to Starship Hospital, or Rescue Helicopter.

Police investigating the crash have ruled out weather, speed, alcohol and road conditions as likely factors in the accident.

Western Bay of Plenty road policing manager Senior Sergeant Ian Campion says police believe Tracey was using her cellphone while driving.

'We also believe she was not wearing her seatbelt. Our preliminary investigation show these factors contributed to the crash.”

Police are still investigating and Ian says other factors may come to light.

'My concern is this is the third fatal on that stretch of road this year, and the sixth [in the Western Bay] for this year.

'Six was our entire total for 2013. My staff and I are gutted at the number of fatal crashes and we urge people to drive safely on the roads.”

With the exception of one that involved a medical condition, Ian says all the fatal crashes are avoidable.

This year there has been a total of 279 crashes in the region. In 2013, there were 867 crashes for the whole year with six deaths.

Road policing assistant commissioner Dave Cliff says April was the worst month for road deaths in New Zealand with figures reaching triple digits.

'Frustratingly, it's still the basics – drinking and driving, going too fast for the conditions and not wearing seatbelt, or a combination of all three – that is needlessly killing large numbers of New Zealanders on the nation's roads every week.

'While the cast majority of road users are doing things right, some are still making all the wrong decisions, with enormous cost to themselves, their families and other innocent road users.”

So far this year, 103 people have died on NZ roads - 15 more than the same time last year.

At the current rate, Dave says at least another 200 people will die and another 1900 will be hospitalised for more than a day by the time we reach the end of the year unless all of us do our part, whether as drivers, passengers, mates or family.”