The Moscow-installed administration of Donetsk said yesterday that at least 25 rockets were fired at the region in the attack.
Russia’s TASS state news agency said at least 15 people were injured.
But Ukraine’s defence ministry said as many as 400 Russians were killed there after a building containing many men was struck.
If is thought it could be Russia’s single biggest loss of life since the start of the invasion last February.
Igor Girkin, a former commander of pro-Russian troops in east Ukraine who has emerged as one of the highest profile Russian nationalist military bloggers, also said the death toll was in the hundreds. Ammunition had been stored in the building, which detonated when the barracks was hit, it was reported.
“What happened in Makiivka is horrible,” wrote Archangel Spetznaz, another Russian military blogger with more than 700,000 followers on Telegram.
“Who came up with the idea to place personnel in large numbers in one building, where even a fool understands that even if they hit with artillery, there will be many wounded or dead?”
A source close to the Russian-installed Donetsk leadership told Reuters the casualty reports were exaggerated and the death toll appeared to be less than 100.
Vladimir Solovyov, a Russian presenter, wrote on Telegram "losses were significant... but not even close" to 400.
Hours after the strike in Makiivka, Kyiv came under fire from Russian strikes. A drone and missile attack targeted critical infrastructure.
He said 22 drones were destroyed over Kyiv, three in the outlying region and 15 over neighbouring provinces.