A bus crashed into an Auckland shop, injuring three people on Friday.

A man pushed his two children out of the way moments before a bus ploughed into a shop on Auckland's North Shore.

Inspector Kai Shao said three people - a father and his two children - were walking across a pedestrian crossing on the corner of Birkenhead Ave and Hammond Place when the bus came towards them about midday on Friday.

"The father got struck by the bus as he pushed the children away," Shao said.

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The children were not injured by the bus but were taken to Starship Hospital as a precaution while the father was taken to North Shore Hospital where he was treated for moderate injuries, he said.

The bus driver was "quite shaken" and co-operated with police, he said.

Matt Rosenberg A family of three were injured after the bus crashed into a shop on Birkenhead Ave, a shop owner says.

"We talked to the bus driver and she gave her side of the story."

Police gave the bus driver a breath test and found no alcohol in her system, Shao said.

"It's a miracle no one got seriously hurt," he said.

Cameron Hicks The AT metro bus crashed into a shop on Birkenhead Ave.

Nicson's Pet Shop owner Susan Huang said she raced outside when she heard a loud crashing sound to see the two children crying and screaming.

"Their dad was just lying in the road - the public all helped bring the kids out of the way and help the family until an ambulance arrived," Huang said.

Nick Dai who witnessed the crash, said he heard a "big bang".

Matt Rosenburg Birkenhead Ave was closed while a tow truck removed the bus wreckage.

"I think the bus just tried to avoid the people on the pedestrian crossing, the sound it made was very loud and I'm still feeling very shocked."

Junior Unlayao works at the bakery next door to where the bus ended up.

Unlayao said he just happened to be looking out the window when the crash took place.

"It happened so fast. It was like a movie. It's tragic," Unlayao said.

Karen Gibson, who was collecting for charity on the sidewalk at the time, said she saw the bus go across the crossing and hit the people who were on it.

The bus was sitting at the stop but when it went to take off it went across the centre of the road and kept going into the shop, she said.

A St John Ambulance spokeswoman said two ambulances were called to the scene at 11.53am.

A police spokesperson said there were no reports of anyone on the bus or inside the building receiving injuries.

The bus crashed into Unitec's Free4U Computing facility, which offers free introductory self-directed courses for the community.

Unitec spokesman Nick Wilson said there was a class with about three students in the shop at the time of the crash.

"The team don't think anyone from Unitec was hurt. We did have a small class in session at the time with several students, all of whom we believe were uninjured.

"Our health and safety and security teams should be arriving there now," Wilson said.

Auckland Transport spokesman James Ireland confirmed an AT Metro bus was involved in the crash.

He said it was still too early to determine exactly what happened but it looked like the bus had gone across the pedestrian crossing, from one side of the road to the other, and then into a shop.

"There's nothing else we can say right now, it's a police matter."

The road is now open in both directions but a small cordon around the building involved remains.

Police confirmed the Commercial Vehicle Safety Team is investigating the incident and the driver is being spoken to as part of their inquiries.

This was the second crash on Auckland's North Shore on Friday.

One person was killed and another injured on the Albany expressway about 6am.