The incident was known about on Sunday but the scale of the deaths has just been revealed by both sides.
Hundreds of Russia’s mobilised troops were killed in a Ukrainian HIMARS strike on a barracks in Russian-occupied Makiivka in the eastern Donbas region, minutes before midnight on December 31.
This happened as Russian missiles and drones rained down on Kyiv, Ukraine at the exact moment Russian president Vladimir Putin was delivering his televised New Year address.
There have been contradictory claims about the losses. Ukraine's military command puts the number of Russian deaths at up to 400, with 300 wounded, while Moscow sources suggested lower figures in the dozens but do admit to a major loss of life, Daily Mail reports.
It was initially impossible to verify the claims but it is clear from both sides that Russia suffered a grievous blow in the latest embarrassment suffered by Moscow's armies since the start of the invasion on February 24, 2022.
The incident was known about on Sunday but the scale of the deaths has just been revealed by both sides.
Russian commanders were among those killed, reports say.
Staunchly pro-Kremlin Ukrainian blogger Anatoly Shariy posted in dismay: 'There are SEVERAL HUNDRED killed in Makiivka.'
He added sarcastically: 'Someone smart put them all together in one place.'
Russian pro-war sources said two HIMARS missile strikes hit the barracks in Makiivka, while the Moscow-installed administration of the Donetsk region in Ukraine said on Sunday that at least 25 rockets were fired at the region overnight on New Year's Eve.
The Russian defence ministry did not immediately respond to a request for comment. In its daily report yesterday, it claimed that it had destroyed seven HIMARS rockets, including in the area of Makiivka.
A dramatic video posted online from the night of the attack shows a family watching Putin's address on a smartphone as they prepare to eat a traditional New Year meal, minutes before midnight.
A woman is on the balcony of her residential block and returns screaming in terror as an incoming attack targets a building nearby, which was later revealed to be a vocational school that was turned into a barracks for Russian forces.
From elsewhere, a Ukrainian video showed a soldier in a festive Santa hat as a HIMARS missile is launched around the time of the Makiivka strike. The HIMARS rocket system behind him has been decorated with Christmas lights.
“According to a number of sources, we can talk about 50 to 70 people [dead] at the moment. The building is completely destroyed,' reported the Grey Zone outlet which is linked to Putin ally Yevgeny Prigozhin, head of the Wagner private army.
“Of course, we are not talking about 500 to 600 dead, this is the enemy's propaganda. But still there were more than 100 people in the building, approximately 120 to 150. Even our most positive channels evasively refer to losses as ‘significant, large and heavy.’”
Videos highlight the total destruction of the school premises where the Russian mobilised forces were reportedly barracked.
HIMARS - which stands for High Mobility Artillery Rocket System - is a US-made launcher which can fire six guided missiles.
The Romanov Light channel said ammunition was also detonated at the barracks - 'hence such destruction'.
Military blogger Boris Rozhin told of 'a substantial number of dead and wounded'.
Earlier reports had said there were four dead and around 50 wounded.
Ukrainian source Obozrevatel said that HIMARS had destroyed 'hundreds of invaders'. 'The number of dead is still unknown. According to various estimates, there were from 150 to 700 occupiers at the base during the attack, most of whom were allegedly mobilised from Saratov.
“According to the Strategic Committee of the Ukrainian Armed Forces, 400 Russian soldiers were killed, and about 300 were wounded.”
Daniil Bezsonov, a senior Russian-backed official in the Moscow-controlled parts of the Donetsk region, said that there was a strike on a vocational school, which according to preliminary information served as military personnel quarters.
The attack, Bezsonov said, happened two minutes after midnight on New Year's Day.
“A massive blow was dealt to the vocational school from American MLRS HIMARS. There were dead and wounded, the exact number is still unknown,” Bezsonov said on the Telegram messaging app. “The building itself was badly damaged.”
Obozrevatel claimed that senior commanders were among the dead. The Russians were searching for 'traitors' who had revealed the location of the barracks.
Pro-war Russian sources angrily criticised commanders for gathering so many soldiers in one place, making them a clear target for attack.