One person has died in a "huge" explosion at a waste disposal factory in south Auckland.
Firefighters are at the scene – Salters Cartage in Wiri – and say the explosion was caused by a welding accident on the fuel tanks.
Salters Cartage owner Ron Salter confirmed to 3 News the victim is one of his workers, and the explosion happened while two contractors were working at the site on Bolderwood Plc.
"They were here to do measurements and were here to do welding, in the office and it blew all the windows in the office, so it's done substantial damage," Mr Salter told RadioLIVE.
Mr Salter said there were 14 staff on site at the time of the explosion, which happened just before 2pm.
Police Inspector Julia Lynch confirmed to 3 News other staff at the factory have been evacuated while the scene is secured.
Two ambulances and a rapid response vehicle were sent to the scene. At least 50 police officers and seven fire crews were also at the site.
One person was treated for minor injuries, while a third suffering from asthma was treated for smoke inhalation.
A stairwell attached to the back of the tank that exploded was blown clean off, and landed on nearby cars causing extensive damage.
A piece of the exploded tank (3 News)
Several people phoned 3 News to say their homes in Wattle Downs and Manurewa shook with the force of the explosion.
A man, identified as 'Clive', called RadioLIVE this afternoon, describing the explosion as "mammoth".
"I mean, it nearly blew me off my feet," he said.
"The shockwave roared through the shop, shrapnel flying through the air."
Another witness working nearby told RadioLIVE it felt like something hit the building next to him.
"It was unreal, I was sitting in the truck just having my lunch while I was getting loaded, and then the side of the building just rocked. It sounded like something just hit it."
The force of the explosion damaged the roof on a nearby vehicle and tore pictures off the walls of a house.
Police say the cause of the explosion is unclear, and WorkSafe NZ are conduction an investigation.