He said the person who was trapped has now been released and taken by helicopter to hospital.
Allan believed the two men were workers and the owner of the company was at the scene looking "pretty cut up" about what had happened.
The Herald believes the truck is owned by waste management company SJ Allen. Owner Simon Spark said he was not prepared to comment at this stage.
"We're still in shock and grief."
Allan said Kiwi businessman Graeme Hart had a multi-million dollar property about 300m from the accident and it was quite an affluent street.
There is a scene guard in place and WorkSafe will be notified.