The crash took place at the intersection of Mt Eden Rd and Bellevue Rd shortly before 3.30pm on Tuesday and involved a white Nissan Cube and a double-decker Auckland Transport (AT) bus.
Call acting Sergeant Colin Nuttall on (09) 481 0773 if you have information.
Chris Tobin, 51, died in the crash minutes from his Mt Eden home and his two young children were hospitalised. Life support for 1-year-old Jack Tobin was turned off this morning and a family member confirmed he had since died.
Jack's 2-year-old sister Elle is in a stable condition in hospital and expected to make a full recovery after Tuesday's crash.
A Givealittle page has been set up to raise money for his devastated wife Olivia and their children. At the time of writing it had raised nearly $10,000.
Tobin is suspected to have suffered a medical event before the crash on the corner of Mt Eden Rd and Bellevue Rd.
His car crossed a median strip and collided with a double-decker bus.
The Givealittle page says Tobin, known as Tuffa, was just minutes away from his Mt Eden home when the crash happened.
"Chris was so full of life, he had one of the biggest grins and a heart full of so much love to all those around him," the page reads.
"He was a devoted family man."
Tobin had three children with Olivia and two older sons from a previous relationship.
"This Givealittle page is one way we can somehow help this beautiful young family get through this terribly tough time and to show them our support.
"Our hearts and prayers go out to you and the kids, Olivia.
"We all love you dearly."
Auckland Tramways Union president Gary Froggatt earlier told the Herald he understood the driver of the car had a medical event, swerved across the median strip at some speed and into the oncoming bus.
The police, when asked about the possible cause of the crash and Froggatt's statement, said they were continuing their investigation and couldn't comment until it was completed.
Froggatt said the bus driver, who is married with children and lives in Mangere, had suffered the sort of trauma that would live with him forever.
About half a dozen passengers were on the bus when it crashed. Two suffered minor and moderate injuries and were taken to Auckland Hospital.
