Beban said he could hear children's crying coming from the back seat of the car. A toddler in a party dress was brought out of the back seat and attended to by emergency services at the scene.
A baby was also brought out. He said the baby appeared to stop breathing but ambulance staff, who had just arrived, were able to intervene.
"In that short time the guy passed away," he said. "The sad thing is someone is waiting at home for their daughters and maybe their husband."
An off-duty nurse and paramedic were at the scene of the crash shortly after it happened and Beban said he was thankful they had been there.
Heavy cordons are in place with diversions at Valley and Onslow roads.
Police have advised motorists to stay away from the area while the serious crash investigators are at the scene.
A green tarpaulin is covering the white car which is on the side of the road. A witness said the front appears to be either missing or crumpled to such an extent that the car looks about a third too short in length underneath.
The bus remains in the middle of the road. The front of the Metro double decker bus is completely destroyed and what's left of the front bumper is hanging off on the road. Shattered glass is everywhere.
The bus involved was a double-decker NZ Bus which is contracted to Auckland Transport. It was running on the 277 route heading down Mt Eden Rd from Three Kings toward the city and Britomart.
St John northern spokeswoman Jennifer Porter said two children were taken to Starship Hospital in a critical condition.
She confirmed one person had died at the scene. A patient with moderate injuries and one with minor injuries have been taken to Auckland City Hospital.
Epsom MP David Seymour has sent his condolences to the families of those involved.
"This is an unimaginable tragedy, involving tiny children in the heart of Mt Eden on a low speed road. My heart goes out to those involved.
"We should also pay tribute to those fast acting members of the public who helped mitigate the tragedy.
"No doubt there will be questions about how this was able to happen, and they will be answered by the correct authorities. For now our thoughts should be with the families affected by this tragedy.
