Ms Brown is the director of the Coffee Chick mobile espresso, and was driving her black Toyota with her company's logo printed on the side.
The Herald has learned that detectives have joined officers from the Waitemata serious crash unit to investigate Ms Brown's death.
Her car and the white Isuzu truck collided at 7.22am.
A police source said it appeared the truck was travelling downhill. The collision occurred near a bend in wet conditions, and the impact seriously damaged the side of Ms Brown's vehicle.
Senior Station Officer Simon Shields from the Kumeu Volunteer Fire Brigade said Ms Brown was "heavily entrapped" in her vehicle when his crew arrived at the scene.
They used cutting equipment to pull the vehicle apart to free her.
St John Ambulance paramedics worked on her, but she died at the scene.
Police said last night that it was too early to say if any charges would be laid.
It was also too early to speculate on the specifics of the crash including how fast the truck was travelling.
Read more: Easter road toll worst in three years
The young businesswoman was the second holiday weekend fatality for the Rodney district.
Last Thursday night, hours after the Easter road toll period began, Helensville mother Alofaifo Afaese was killed near Kumeu when the vehicle she was a passenger in collided with another car.
Mrs Afaese, 40, was not wearing a seatbelt, and as the vehicle flipped and rolled after the impact she was thrown through her window and died instantly.
Her husband, who was driving, and two young boys believed to be the couple's sons were taken to hospital with injuries.
Rodney police area commander Inspector Scott Webb urged motorists to "slow down and watch those following distances, especially on rural roads".
Last night, the Easter road toll stood at four.
Traffic delays tested the patience of motorists in Waikato as holidaymakers returned home after the long weekend.
Traffic was heavy but steady on Auckland's motorway network, and Wellington drivers faced a slow crawl from Ohau, near Levin.
Police say there were no major crashes, and long tails of traffic were caused by the number of cars on the road.
"We've had one complaint about a cheeky driver trying to go up the shoulder of the expressway and pass cars,"said Senior Sergeant Rupert Friend of Hamilton.
"Of the huge number of motorists out there, most have been pretty good, but we've still got a lot of complaints about peoples' behaviour."
