It began with a "massive bang", followed immediately by smoke, screams and children crying for their mums.
Office worker Michelle Sterling ran outside and saw the back of the No 942 bus sticking out of Unitec's Free4U computer training facility shop in Birkenhead Ave, the main shopping street in the North Shore suburb of Birkenhead.
There was "lots of smoke" and on the pedestrian crossing in front of her lay a man — blood pouring from his head — and with a distressed girl of about 10 by his side. A woman and a preschool-aged boy were also involved in the incident.
Dozens of workers, motorists and pedestrians rushed to help when the group of four — believed to be parents and their two children — were caught up in the drama while crossing the road just before noon.
Police later confirmed a man was taken by ambulance to North Shore Hospital with moderate injuries and two children were taken to Starship Hospital as a precaution.
Sterling was one of the first on the scene, her first act crouching down — her heart in her mouth — to see if anyone was under bus which had suddenly hurtled across the road, through a barrier and bench seat and into a shop.
"I could just see glass and debris, but not people, thank goodness."
She then cradled the injured man's bloodied head while also trying to put her arm around the little girl.
"He just kept saying 'my wife and kids, my wife and kids' over and over, because I only had one of the kids there. A colleague said 'your wife is okay'."
Sterling called out for medical help and said two nurses in a nearby cafe rushed to help.
"One of them had pink tights on and she was amazing ... in control."
As others arrived to help, among them a doctor who ran from a nearby medical centre, Sterling, blood staining her blouse, turned her attention to the boy.
"I'm a mum and you think of your own kids straightaway. He was about 3 and had quite a severe graze on his head. I took his little back pack off and wrapped my arms around him.
"He was crying and I could hear his little heart going boom, boom, boom."
Sterling said another helper told her the injured man had said he and his wife were also bus drivers, but she had not confirmed this.
Nicsons Pet Shop owner Susan Huang also ran to help, taking pet blankets to keep the injured warm.
"The children were very shocked. They kept calling 'mum, mum', because she was checking on what's happening to her husband."
The driver of the crashed bus, who, along with their passengers, was not injured, is being spoken to by police as part of their investigation.
The road has reopened in both directions after a heavy haulage tow truck pulled the Auckland Transport bus, its front windscreen smashed, from the badly-damaged shop.
Three students inside the shop at the time were also unhurt.
Other motorists were also lucky to escape harm, among them 20-year-old Allstar Plumbing apprentice Isaac, who had stopped at the pedestrian crossing for the family when the bus swung across in front of him and into the shop.
"I'm not sure if they hit the accelerator instead of the brake. It came out of nowhere. I was lucky not to get hit. If I had been two metres ahead I would've been hit directly on the driver's side."
The bus passengers all got out "real quick". He believed the bus driver was a woman, Isaac, who did not want his full name used, said.
Aravinda Harinarayanan was in a vehicle behind Isaac and told the Herald he was a man jump out of the way, narrowly avoiding being struck, before the bus struck the injured man and his child — whom he described as being of Asian ethnicity.
"It was a horrifying experience. The bus kept turning right all the way and was accelerating continuously," Harinarayanan wrote in an email to the Herald.
"It later brushed off the white van and into the shop ... I got out of the car and rushed to see [the injured man]. His kid was okay but shocked and crying out loud. She had blood stains on her face, but that was from her father."