Fire crews are making sure a massive factory fire in south Auckland that broke out on Thursday night doesn't flare back up.
Witnesses say they heard small explosions coming from the concrete manufacturing building in Penrose after it caught alight just before 8:35pm.
Video showed the building completely engulfed in flames, with plumes of thick smoke filling the air.
The blaze has now been extinguished, and a new crew is at the scene to make sure it doesn't flare up.
Auckland fire area commander Richard Toomey says at one stage overnight, 50 firefighters were battling the flames.
"It's one of the biggest ones we've had in this area for a while - we're quite lucky that we're not having a lot of large fires at the moment but this is definitely one of the bigger ones that we have had this year."
No one is thought to have been inside the building, a fire service spokesperson confirmed to Newshub.