There were around 20 passengers on board, all of whom got on the next bus on the route.
"The driver is quite shaken and will be taking tomorrow off work. He will be given all the support he needs," Ireland said. "The bus has been released and is being taken back to the depot."
Traffic in east Auckland has been further held up by a three-car crash at the intersection of Te Irirangi Drive and Ti Rakau Drive around 5.20pm.
A police spokesman said traffic was still flowing and people were standing outside their cars. It is not known if there were any injuries as a result of the second crash.
A third crash was holding up traffic in both directions on Avimore Drive near Aberfeldy Ave.