A police spokeswoman said emergency services were called to the crash in Police St, near the intersection with Crawford St (State Highway 1) about 7.55am.
The truck struck a pedestrian before hitting several cars, the spokesman said.
The pedestrian, understood to be a 19-year-old man who worked at a nearby store, died at the scene.
The police serious crash unit was at the scene, working to piece together exactly what happened, the spokeswoman said.
The intersection of Crawford St and Police St remained closed until about 5pm.
A witness said the driver was not in the truck at the time of the incident, but appeared to be talking to mechanics at an auto parts store in Carroll St when the truck began to move.
Damage could be seen to the side of the Forno’s Auction House building in Police St.
Images from the scene suggest the pedestrian had been walking in Police St, between Princes and Bond Sts.
A badly damaged white Subaru was nearby and appeared to have been spun around by the force of the truck.
Across Crawford St, a red hatchback appeared to have been wedged underneath a black SUV by the force of the truck coming to a stop.
A witness who came across the scene shortly afterwards said the incident was "pretty crazy" and it was heartbreaking a person had died.
Cars were piled up on top of each other in Police St, between Crawford and Vogel Sts.
"What has happened is a tragedy for all involved and this is the first incident in the 30 years my family has owned the company," Mr Gerring said.
He extended condolences to the family and friends of the pedestrian who died and acknowledged the assistance given by members of the public and emergency services.
The company was providing support for the driver involved and would be fully co-operating with police, Mr Gerring said.
A Fire and Emergency New Zealand spokesman said crews were called to reports of a truck and trailer unit hitting multiple cars.
Crews from Lookout Point, Willowbank and Dunedin City stations assisted at the scene, the spokesman said.
