Two men are recovering from burns after the power pylon they were working on exploded, cutting electricity to nearly 800 homes.
The Electrix employees were elevated in a cherry picker on Sandspit Rd in Warkworth, north of Auckland, when the pylon exploded about 3pm.
Constable Kevin Blair said the men appeared to have been injured in a flash explosion that left them both with burns to the face and neck.
"It appears they had all the right equipment because their eyes were fine - you could see where they had their glasses on. They had quite severe burns to their faces and necks and top of the shoulders, but otherwise they should be fine."
He did not know if they had any electrical current go through them.
"We couldn't see any entry or exit points [so] as far as we could tell it was a flash explosion."
Mr Blair said one man had "all the skin on his face burned off ... It was all pink," while the other man had blisters on his neck.
"One of them obviously got more of the blast than the other."
Colleagues of the men had lowered the cherry picker after the blast and called 111.
They were flown to Auckland Hospital by the Auckland Westpac Rescue helicopter.
Sandy Hodge, a spokeswoman for Vector, which contracts Electrix to maintain the northern part of the network, said the men's burns were superficial.
The company was supporting the two men and their families.
"Our thoughts are with the families at this time, even though we have been told the injuries are superficial burns it's still a nasty thing to go through and our thoughts are with them."
Police had referred the incident to the Ministry of Business, Innovation and Employment who would investigate.
Advanced paramedic Shand Park said the pair were "walking and talking" when help arrived, and he expected them to make a full recovery. He said they were very lucky.
"It could have blown their heads off."
The cause of the explosion was unknown, Electrix investigator Morne Green told the Herald.
"We have no idea if it was human error or a line fault, that's what we are investigating."
There were dozens of staff at the scene last night, and two of three plastic attachments - that link wires to the pylon - were black and melted.
The blast cut power to 768 dwellings in Warkworth and Matakana, and 39 were still disconnected at 6 last night.
Sandspit Rd resident Don Hawkings said it sounded like a bomb blast. "I was in the garden and there was a big [explosion] sound like something had blown up."