MAKIIVKA, Ukraine (Reuters) - A Ukrainian missile strike on Jan. 1 against a vocational school in the Russian-controlled Donetsk region of Ukraine housing mobilised Russian troops has become one of the bloodiest incidents of Russia's nearly year-long war in Ukraine.
What do we know, and what do we not know, about what happened?
The strike on Professional Technical School No. 19 in Makiivka, a twin city to the regional capital of Donetsk which has been controlled by Russian proxy forces since 2014, occurred at 0001 on New Year's Day, Daniil Bezsonov, a Russian-installed Donetsk official, said.
Russia's defence ministry said Ukraine struck with six U.S.-made HIMARS rockets.
The governor of Russia's Samara region said that many of the dead soldiers were locals.
Unconfirmed footage circulated on social media purportedly shows residents watching Russian President Vladimir Putin's midnight address before running for cover as missiles strike the ground nearby.
Reuters photographs from the scene show the ruined remains of the school.
Reports of casualties vary. Reuters was unable to independently verify how many people were killed.
Russia's defence ministry said on Monday that 63 soldiers had been killed in the strike, an assessment echoed by a source close to Donetsk's Russia-installed separatist leadership, who told Reuters that dozens had died.
The ministry acknowledged the attack only in the final paragraph of a 528-word daily roundup, more than 36 hours after the attack took place.
Russia has consistently underplayed its casualty figures, including claiming that only one man died during the sinking of the battleship Moskva in April.
Ukraine has claimed a far higher casualty figure, saying that around 400 died. A number of Russian military bloggers, who have gained large followings through mixing pro-Kremlin advocacy with unvarnished information on the state of the front, have also given casualty figures closer to the Ukrainian number.
In a post on the Telegram messaging app, Igor Girkin, a former FSB officer instrumental in starting the initial 2014 war in the Donbas, said that there were "many hundreds" of killed and injured.
Girkin said that ammunition and military equipment had been stored in the buildings, contributing to the strength of the blast. He blamed Russia's "untrainable" generals for the losses.
Grey Zone, a Telegram channel linked to the Wagner mercenary outfit, said that around 500 men were billeted in the complex.
In footage circulated on social media and geolocated by Reuters, the vocational school, a large complex of Soviet-era buildings, appears virtually razed as emergency service workers sift through rubble.
Coming at the climax of the new year's celebrations, the most important holiday of the year in Russia, the attack has resonated within Russia.
A report by state-owned news agency TASS, citing Donetsk officials, saying that Ukrainian forces were able to identify the target from soldiers using their Russian mobile phones has provoked anger among Russia's military blogger community.
"As expected, the blame for what happened in Makiivka began to be blamed on the mobilised soldiers themselves. You see, they turned on their phones and got spotted," wrote Grey Zone, a Telegram channel linked to the Wagner Group mercenary outfit.
Grey Zone went on to blame commanders for lodging large numbers of soldiers in a building vulnerable to artillery fire.
In a post on Telegram, Sergei Mironov, leader of a Kremlin-loyal party in Russia's parliament, said that an investigation was necessary to determine whether "treachery or criminal negligence" was behind the strike. He said that officials responsible should be prosecuted.
(Reporting by Reuters; editing by Guy Faulconbridge and Nick Macfie)