The troops were killed as they gathered in a southern village for a military commemoration, the officials said.
Russian missiles struck a group of Ukrainian soldiers at an award ceremony in southern Ukraine, killing some and leaving others wounded, two senior Ukrainian military officials said Sunday.
One of the military officials, who declined to be named because he was not authorized to disclose information, said that two missiles struck in succession on Friday morning as soldiers from the 128th Mountain Assault Brigade gathered in the village of Zarichne, near the front line in the Zaporizhzhia region. The soldiers were there to mark Artillery Day, one of a series of days in Ukraine that honor branches of the military.
It was not possible to independently confirm the number of casualties or the nature of the strike.
In a statement on Facebook late Saturday, Ukraine’s military said that Russia had launched “sneak attacks” on 26 settlements in Zaporizhzhia and targeted personnel of the 128th brigade with a missile, “resulting in the deaths of servicemen and various degrees of injuries to local residents.” It did not give further details.
Viktor Mykyta, the head of the military administration in Zakarpattia, a western region from which many members of the brigade came, confirmed the strike and deaths, and called for three days of mourning. “I recommend visiting the churches and praying for our defenders,” he said on the Telegram messaging app.
Russia’s Ministry of Defense said on Sunday that its forces had been active in the Zaporizhzhia region but did not refer directly to a strike in Zarichne.
Ukraine and Russia have incurred substantial casualties in fighting since Ukraine launched a counteroffensive in June to recapture ground in the south and east. Both sides detail enemy losses in daily reports, but it is highly unusual for either to disclose its own casualties.
Ukraine’s defense minister, Rustem Umerov, said on Facebook late Saturday that he had ordered an investigation into the Zarichne attack, adding, “Our enemy is an insidious terrorist.”
It is unclear why the Ukrainian authorities decided to speak publicly about the strike, but it would at least partly reflect the gravity of the episode.
It follows an acknowledgment by the commander of Ukraine’s armed forces, Gen. Valery Zaluzhny, that his troops were locked in a stalemate with Russia along the front line with no imminent prospect of a breakthrough.
The comments, made in an interview published last week in the British magazine The Economist, were unusually candid.
The office of President Volodymyr Zelensky criticized General Zaluzhny on Saturday for making the comments and, while the commander has not responded publicly, the two remarks suggest a potential rift in Ukraine’s top civilian and military leadership at a difficult moment for the country’s war effort.
The absence of a decisive battlefield victory, coupled with military losses such as the one on Friday, presents Ukraine’s government with a strategic test, particularly at a time when some Republicans in Congress have argued that the United States should stop sending it military aid.
In a speech on Saturday, Mr. Zelensky made no reference to the 128th brigade, though he did thank “everyone who has dedicated their life to ensure Ukraine’s endurance.”