Lanes have been blocked after a bus crashed into a barrier on Newton Road in central Auckland.
Police and emergency services responded to the crash reported about 8.04am in Ponsonby.
One person has been taken to hospital with minor injuries. St John said it assessed and treated 24 patients in total at the scene; all were classified as minor injuries.
All passengers were off the bus, police said.
St Mary's College principal Sarah Dwan confirmed that students from the college, who were on their way to school were on the bus.
She said the students were safe and responding well.
"Support is being provided for the students and their families and we will continue to support all involved.
"A staff member happened to be behind the bus on their way to school who was able to stop and provide support to our students."
Witnesses say the bus is dangling off a bridge.
One of the witnesses at the scene of crash says all the children on board have been got off the bus and into another.
She says the "bus has inexplicably breached a motorway barrier".
It seems "to be a major incident" and traffic is banked up.
"It looks very precarious," Bridget Burke told Morning Report's Kim Hill.
The lanes heading towards Ponsonby are blocked, and one lane towards Newmarket remains open.
Motorists are asked to avoid the area or expect delays.