A branch coming down on powerlines has been blamed for a power cut that affected 3900 Rotorua homes.
Unison customer relations manager Danny Gough said the incident happened about 5.20am this morning, causing power to go out around the Springfield and Clayton Rd areas.
Other areas reportedly affected included Westbrook, Utuhina, and Pukehangi.
Mr Gough said when the branch came down it caused "a bit of a surge" and an explosion further up the network.
"That's why it was more of a larger event."
All customers had their power restored in about 40 minutes, he said.
One of the Rotorua Daily Post's readers commented on Facebook: "Heard an explosion, Westbrook area then power out, sounded like a transformer going up?"
Others who commented said: "Heard the explosion and lights flickered but still got power", "6.15am heard big bang, scrambled to light fire for a coffee", and "Had power fluctuation and set off my home alarm".
Commenters also thanked Unison for its work getting the power back on and sorted quickly.