Almost 500 miners are trapped underground after a shell hit an electric substation near the site in war-torn east Ukraine.
Emergency services were alerted when Donetsk's Zasyadko coal mine, one of eastern Europe's largest, lost all power in the blast.
It comes just over a fortnight since a similar incident briefly trapped 300 miners on January 11.
A Donetsk region emergencies ministry official said: "When the power went out, there were 496 miners underground. Right now, we are making preparations to bring them to safety."
Another ministry official was quoted by a pro-rebel website as saying the lives of the miners are not in danger and that the first evacuation had already begun.
An unnamed separatist "defence ministry" official in Donetsk said 110 miners had been brought back to the ground in the first minutes after the power outage.
The war between pro-Russian militants and government forces in eastern Ukraine has claimed nearly 5,100 lives since it began nine months ago.
Latest Stories
-
Stop forcing workers to strike before honoring agreements – Justice Yankson urges gov’t
10 minutes -
We may resume strike if gov’t doesn’t honour its part of the bargain – GRNMA
37 minutes -
‘I will leave it to Otto Addo to assess how I fared in the Unity Cup’ – Bonsu Baah
2 hours -
Livestream: Newsfile discusses nurses strike, NSA probe, radio stations shutdown
2 hours -
Infantino: FIFA Club World Cup marks ‘new era’ for football
4 hours -
How Trump’s Africa strategy may become a double-edged sword
4 hours -
Why the expanded FIFA Club World Cup is worth trying
4 hours -
Mahama promises to end power fluctuations in North East Region
4 hours -
Battle of the Beasts: American Tabiti destroys Jacob Dickson to win WBO Africa Cruiserweight title
4 hours -
Speaker defers ruling on Afenyo-Markin’s government mass dismissals request
5 hours -
Battle of the Beasts: Ahmed Abdul floors Haruna Mohammed to win national cruiserweight title
5 hours -
Manasseh Awuni’s heartfelt message to Mahama on the Zoomlion contract action
5 hours -
Battle of the Beasts: Theo Allotey batters Daniel Gorsh to win WBO African Bantamweight title
5 hours -
Why always fuel: The growing burden of energy levies in Ghana
5 hours -
Asantehene urges chiefs to offer lands as equity for farming
5 hours