Terrifying footage has emerged capturing a packed school bus careening into an Auckland motorway overpass during morning rush hour.

The bus can be seen pulling onto the Newton Rd overbridge before continuing to sweep in a circle, crashing through the barrier and left dangling mid-air.

The whole dramatic incident unfolds in just five seconds.

Oncoming traffic is brought to a standstill as the bus is left straddling the busy motorway overbridge on Auckland's spaghetti junction.

Within minutes, emergency services rushed to rescue the school students from Ponsonby's St Mary's College who were trapped inside the precariously balanced bus.

St John Ambulance said 24 people were assessed for injuries and one was taken to hospital with minor injuries.

Bus carrying school students was left dangling on the motorway overpass this morning in Auckland. Photo / Matthew Lietz

The crash, which happened at 8am, caused extensive traffic delays through Khyber Pass Rd and in Ponsonby.

The high school students on the bus were transferred to a nearby bus after being checked by St John ambulance staff.

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Firefighters had to cut apart parts of the bridge fence and needed to hook the bus up to pull it out.

An inflation device was placed under the vehicle to raise it up and then winch it to safety.

Firefighters can be seen moving the bus back on the footpath. Photo / Cheree Kinnear

St Mary's College principal Sarah Dwan praised first respondents who came quickly on the scene to help students trapped in the bus.

Dwan said it was fortunate that a staff member was in a car behind the coach and was able to offer immediate help.

"All our students are safe and well, and we are incredibly proud of how they have reacted and responded.

"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."

The Newton Rd overpass remained partially closed this afternoon as teams inspected and worked on repairing the damaged barrier.

Auckland Transport said the vehicle recovery operation had now been completed but motorists were unable to use westbound lanes.

Bus can be seen halfway through the bridge after the crash. Photo / Matthew Lietz

Coachways New Zealand spokesman Dave Marsden said this morning's bus crash was under investigation at the moment.

He didn't have any reports from either the driver or the police so he was unable to answer any questions.

A police spokesperson said inquiries were ongoing and no charges had been laid at this stage.