One person was injured after an explosion outside a Stihl shop in the Waikato town of Cambridge.
Fire and Emergency New Zealand said a 44 gallon (200 litre) drum exploded at 8.07am this morning.
An RNZ reporter at the scene was told a worker was cutting the top from a large oil drum when it ignited, blowing the lid off.
A colleague of the worker told RNZ he "was very lucky".
One eye witness said she called 111 as she was across the road from the shop when it occurred.
"There was a massive explosion and then black smoke and flames."
She understands that everyone at the shop is ok.
"They are just a bit shook up I think."
The sound from the explosion was heard as far away as two blocks where a worker at the local council said he heard a big explosion and felt the shock wave.
One eyewitness said that the lid of the drum may have been blown up to a block away from the scene.
A St John spokesperson said ambulance staff treated one person with minor injuries, but was not taken to hospital.
Fire and Emergency said the fire was out by the time its crew arrived.