Key Points:

A family is struggling to understand how their mother was knocked down and killed by a bus barely 20m from her front door.

Takapuna mother-of-five Zhuan-di Liu Chen, 58, received the fatal blow from a Ritchies bus full of school students and commuters seconds after leaving home shortly before 8.30am on Thursday.

The accident happened on Wairau Rd, opposite Westlake Girls' High School, a stretch of road Chen had crossed hundreds of times.

No one on the bus was hurt, but the school offered counselling and hot drinks to students and passengers who were on board or had witnessed the accident.

The death has left Chen's husband and five adult children searching for answers.

Daughter Rachel said her mother walked to her bank job most days and crossed the road in that spot regularly. She said it would be hard to imagine her mother running out in front of a bus because she knew how busy the road was.

The family had lived in the house for more than five years after moving here from China six years ago.

Rachel said her father was coping well, but the family had lost a loving and caring mother and wife.

Another daughter, Cherry, said she received the news at university in a phone call from her uncle.

She and two sisters, who live on the North Shore, had called their siblings in China about the funeral.

Cherry said the family was planning to contact police tomorrow. They didn't want someone to blame, but wanted to find out how the incident happened.

Crash investigator Senior Constable Gary Abbott said initial reports suggested Chen had stepped out from behind a car into the bus lane. Although the bus swerved, she was struck and run over.

Ritchies director John Ritchie, said the bus driver had given statements to police, but remained very distressed. "He's due for counselling on Monday. We'll do an assessment and see how he is after that."

Ritchie's understanding was that the driver had swerved and had done all he could to avoid the accident.

"The vehicle was also taken for an inspection to check the brakes. Everything was working," he said.

Such incidents were "absolutely terrible" for drivers, Ritchie said.