Raw video: Smoke billows from cement truck on fire on Auckland Motorway during morning rush hour

A cement truck that caught fire on Auckland's Southern Motorway is causing major concerns for commuters.

The incident happened on State Highway One, southbound, close to the Market Road off ramp just after 6.30am.

Police say the southbound lane is currently blocked and traffic is being diverted to SH20.

They say no one appears to be injured and it is unclear how the truck caught fire.

Compounding morning rush hour delays on the Southern Motorway there's been a 10 car crash at 6.22am close to the Mount Wellington Highway offramp.

Police say the area is now clear but motorists should expect delays and follow diversions which will be put in place.

They say there there appears there were no injuries from this incident.