UPDATED 9.46am: An Auckland plastics factory that went up in flames last night had no sprinklers and no fire detection systems.

Daylight this morning has revealed there is nothing left of Total Plastics in Henderson.

The massive fire there started late last night, and more than a hundred firefighters were called in.

On top of the fire, they had to deal with exploding debris, falling power lines, dense smoke and chemicals.

Total Plastics owner Tony King has just arrived at the scene. 

He hugged several workers and offered words of comfort but wanted to "take it in" before speaking to media. 

A group of about half a dozen Total Plastics workers arrived at the site about 9am but they didn't want to speak to media.  

For Senior Station Officer Chris Delfos, it's one of the biggest fires he's seen.

"The building is totally lost really, it's a total loss, it's quite a large building and unfortunately we haven't been able to save much of it at all."

The blaze is being treated as suspicious.

The Fire Service received dozens of calls late last night as the Total Plastics factory and car dismantling site caught alight.

New Zealand Herald reporter Catherine Gaffaney said residents congregated at the nearby Sunnyvale train station, where all trains had been stopped, to get a glimpse of the action.

"Everyone that has come has heard it from their own homes - some live just a street over and they heard bangs that sounded like fireworks and saw flames."

Eyewitnesses reported mushroom clouds of fire and smoke, loud explosions, and the stench of burning plastic, as 100 firefighters battled the blaze.

Nearby resident Devon Neaves said the explosions and flames were terrifying.

"As soon as the mushroom cloud exploded it sounded like all of Henderson just went woah."

Eyewitness Bailey went down with his Dad to watch the drama.

He told Newstalk ZB he saw several explosions of fuel tanks and acetylene gas bottles.

"There's been a couple of mushroom clouds - big explosions, sparks and smoke."

Robin Wright owns Coating Technologies, a paint supply business separated from Advance Japanese Car Parts by only a driveway. 

He said the couple who owned the business had been at the site about five years. 

"I feel sorry for them because they have worked bloody hard."

The danger from smoke and water run-off from large factory fire in west Auckland last night was serious enough for Civil Defence to take an interest.

Civil Defence went on standby to help in case an evacuation was needed, and to co-ordinate other services including pollution response.