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.

No one was injured and all passengers were off the bus, police said.

Bus crashes into barrier on Newton Road, Ponsonby, Auckland on 16 September 2022.

Bus crashes into barrier on Newton Road, Ponsonby, Auckland on 16 September 2022. Photo: RNZ / Bridget Burke

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.

Bus crashes into barrier on Newton Road, Ponsonby, Auckland on 16 September 2022.

Bus crashes into barrier on Newton Road, Ponsonby, Auckland on 16 September 2022. Photo: RNZ / Mohammad Alafeshat

The lanes heading towards Ponsonby are blocked, and one lane towards Newmarket remains open.

Motorists are asked to avoid the area or expect delays.