A "mini-whirlwind" has lifted the roof from a West Auckland factory, dumped it on power lines and cut electricity to the area, Fire and Emergency says.
Fire and Emergency shift leader Craig Dally said they were alerted to reports of an explosion in Henderson Valley Rd just after 4.30pm.
But the incident was actually said to have been caused by a weather event.
"A mini-whirlwind lifted the roof of a factory and that came into contact with power lines ... it sounds like it did spark because we were called to an explosion."
No one was hurt.