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Washington CNN  — 

“This is genocide.”

That’s how Ukrainian President Volodymyr Zelensky described the shocking images of at least 20 civilian men’s bodies strewn across the street in Bucha, northwest of the capital of Kyiv, following the withdrawal of Russian forces from the area.

Accounts of alleged Russian atrocities, including the horrific images of dead civilians captured by Agence France-Presse, are emerging as its forces retreat from areas near Kyiv following a failed bid to encircle the capital.

“The elimination of the whole nation, and the people. We are the citizens of Ukraine. We have more than 100 nationalities. This is about the destruction and extermination of all these nationalities,” Zelensky said Sunday on CBS News’ “Face the Nation” when asked if Russia is carrying out genocide.

CNN has not been able to independently confirm the details around the men’s deaths.

Russia responds. The Russian Ministry of Defense claimed the extensive footage of dead bodies in Bucha was “fake,” saying “not a single local resident suffered from any violent actions,” during Russia’s occupation of Bucha.

“In the settlements of the Kiev region, Russian military personnel delivered and issued 452 tons of humanitarian aid to civilians,” it said in a statement. A separate statement claimed the footage was staged.

The Russian government has consistently responded to allegations of civilian casualties inflicted by Russian forces with blanket denials.

Human Rights Watch documents alleged crimes. Rape, summary executions and unlawful violence are some of the war crimes allegedly perpetrated by Russian forces against civilians in the occupied areas of the Chernihiv, Kharkiv and Kyiv regions of Ukraine, according to Human Rights Watch, an independent rights group.

HRW said in a statement Sunday that it has documented allegations of war crimes, which “include a case of repeated rape; two cases of summary execution, one of six men, the other of one man; and other cases of unlawful violence and threats against civilians between February 27 and March 14, 2022.” CNN has not independently verified the details of those reports and has requested comment from the Russian Ministry of Defense regarding the allegations.

Urgent appeal at the Grammys. In a taped message shown at the Grammy Awards later Sunday, Zelensky made an urgent plea for support with a speech that began: “The war. What’s more opposite to music? The silence of ruined cities and killed people.”

“Our musicians wear body armor instead of tuxedos,” he said at one point. “They sing to the wounded. In hospitals.”

Zelensky implored those listening to “Tell the truth about war. On your social networks. On TV. Support us in any way you can. Any. But not silence.”

CNN team observes a mass grave site. A mass grave has been discovered in the town of Bucha, CNN found. CNN saw at least a dozen bodies in body bags piled inside the grave. Some were already partially covered.

Bodies were first buried in the grave, on the grounds of the Church of St. Andrew and Pyervozvannoho All Saints, in the first days of the war, residents told CNN. Around 150 people, mostly civilians killed in the fighting around the town, are buried there, residents said. The mayor of Bucha said in public remarks on Saturday that there could be up to 300 victims buried on site. CNN was unable to independently verify those numbers or the identities and nationalities of those buried in the grave.

‘A punch to the gut.’ US Secretary of State Antony Blinken said Sunday that the State Department would help document any atrocities the Russian military committed against Ukrainian civilians.

“You can’t help but see these images as a punch to the gut,” Blinken told CNN’s Dana Bash on “State of the Union” Sunday, responding to the reports from Bucha.

Last month, the State Department formally accused Russian forces of war crimes in Ukraine.

Asked Sunday whether Russian troops were committing genocide, Blinken didn’t go as far as Zelensky.

“We will look hard and document everything that we see, put it all together, make sure that the relevant institutions and organizations that are looking at this, including the State Department, have everything they need to assess exactly what took place in Ukraine, who’s responsible and what it amounts to,” he said.

New investigation coming? The top UN official said an “independent investigation” into the civilians killed in Bucha is “essential” to ensure “effective accountability.”

“I am deeply shocked by the images of civilians killed in Bucha, Ukraine,” UN Secretary-General António Guterres said in a statement Sunday.

More sanctions could be on the way. State Department spokesperson Ned Price, meanwhile, hinted at additional US action against Russia coming “very soon” when asked about Zelensky’s request for greater G7 sanctions in response to the latest alleged atrocities in Bucha.

“When it comes to our sanctions, we’ve always said that we will continue applying pressure on President Putin, on the Kremlin, on all of those around him including oligarchs and cronies who are empowering this war of choice against Ukraine, until and unless the Kremlin deescalates, until and unless the violence diminishes, and until and unless these kinds of atrocities come to an end. So I suspect you will very soon see additional pressure applied,” Price told MSNBC on Sunday.

‘Not enough.’ In a video address later on Sunday, in which he called for an end of Russian “war crimes,” Zelensky said of stronger sanctions against Russia: “I’m sure that’s not enough.”

“More conclusions are needed. Not only about Russia, but also about the political behavior that actually allowed this evil to come to our land,” he added.

Expect the attacks to continue. This is not a “real withdrawal of Russian forces,” NATO Secretary General Jens Stoltenberg said, warning that attacks in Ukraine will continue.

“What we see is not a real withdrawal. But we see that Russia is repositioning its troops and they are taking some of them back to rearm them, to reinforce them, to resupply them. We should not in a way be too optimistic because the attacks will continue,” Stoltenberg told CNN Sunday.

This story has been updated with additional details.