"A commission has been created to clarify all the circumstances of the incident, an investigation is underway," it said yesterday in a translated statement.
The Russian company, also known as Nornickel, said in an update the mine was operating normally at 8pm local time.
Deputy prime minister of the Krasnoaysk region Anatoly Tsykalov told the TASS news agency all three people were found dead with unopened self-protective breathing equipment, Reuters reported.
"Three people died, no one is injured," he was quoted as saying.
"The reasons for the situation are being investigated. There were no technological violations at the mine."
Taimyrsky is aiming to increase ore production from 3.5 million tonnes to 3.9Mt by 2020 through improved performance, according to Nornickel's 2016 annual report.
It said Taimyrsky had an average metal content of 2.3% nickel, 3.5% copper and 7.3g/t platinum group metals.