Moscow's defense ministry said early Friday that its troops and equipment had been withdrawn from the western bank of the Dnieper River — finalizing a humiliating pullout.


MYKOLAIV, Ukraine —  Ukrainian forces swept into the key southern city of Kherson on Friday, hours after Russia said its military had completed a rapid retreat from the area — a humiliating setback for President Vladimir Putin and a major development in the war.


As jubilant civilians flocked to the city's central square, Kyiv said its forces were in control and warned any remaining Russian troops to surrender.


"Kherson returns under control of Ukraine, parts of Ukrainian Armed Forces enter the city," the Main Directorate of Ukrainian Intelligence wrote on its Facebook page. Its message to any remaining Russian soldiers: "You have only one chance to avoid death — to surrender immediately."


The pullout across the Dnieper River that divides the region marks one of the biggest blows yet for Putin, abandoning perhaps the greatest prize of the war he launched nearly nine months ago.


It follows a grinding Ukrainian counteroffensive that pushed Putin's troops back and pounded their supply lines, sparking a race by Russia to evacuate more than 100,000 residents in the area — and then its own soldiers.


Moscow's defense ministry said in a statement reported by state news agencies earlier Friday that its troops and equipment had been withdrawn from the western bank of the Dnieper River by 5 a.m. local time (9 p.m. ET), finalizing their pullout from the city of Kherson and much of its surrounding area.


Kremlin spokesman Dmitry Peskov denied the episode was embarrassing for Putin, who only weeks ago had proclaimed the region's annexation. "Kyiv does not want negotiations. The special military operation continues," Peskov said in his daily press briefing.


In the center of Kherson, the strategic port city seized by Putin's forces in the war's earliest days, video and photos verified by NBC News showed residents chanting as they gathered at the regional administration building to hoist Ukrainian and European Union flags where the Russian flag had flown just days earlier.


But Ukrainian officials remained wary, warning that Russian forces could inflict severe military and civilian damage through artillery strikes and mines left behind as they pulled out.


A deadly missile strike was also reported in the nearby city of Mykolaiv while a key bridge over the Dnieper River was left in ruins in the wake of the Russian exit, according to images and video that emerged Friday and were verified by NBC News.


The damage to the bridge may slow any further Ukrainian advance, but for now its army and local residents were happy to return the country's flag to territory that had been occupied since the early days of the war.


'A major blow'


Retaking Kherson could be a strategically and psychologically crucial victory for Ukraine.


It was the only regional capital city seized and controlled by Russia since its full-scale invasion Feb. 24 and its capture helped ensure access to the coast, allowing the Kremlin to create a land corridor across Ukraine's south. 


It also acts as a vital gateway to the Crimean Peninsula, which Russia has occupied since 2014.


The Ukrainian military has targeted the main Dnieper River crossings for months, making it difficult for Russia to supply forces on the river's west bank. Since they burst through the Russian front lines at the start of October, the Ukrainians have slowly advanced toward Kherson.


Losing the city "is a major blow for the Russians," Christopher Tuck, an analyst in strategic studies at King's College London, told NBC News. 


It made "Putin look weak and it makes Russia look weak," he said.


"It was only a few months ago that Putin was identifying the region of Kherson as part of Russia itself," he added, referring to a declaration from Moscow at the end of September that it had annexed the Kherson region, along with Donetsk, Luhansk and Zaporizhzhia. It came after Russia staged referendums that were denounced by Kyiv and the West as illegal and rigged. 


Tuck said that it was also a boost for Ukrainian President Volodymyr Zelenskyy "because it's an indicator that the earlier gains that Ukraine made in the northeast weren't just a one off and there is more momentum behind his country's military efforts."   


Mykolaiv missile attack


The war is far from over, however.


Russia is firing a staggering 20,000 artillery rounds per day, according to a senior U.S. defense official, while Ukraine is firing from 4,000 to 7,000 rounds daily.


The Institute for the Study of War, a Washington-based think tank, said in a briefing note Thursday that the wet, muddy weather that so badly affected Russian supply lines at the start of the war had returned, adding that Ukraine's harsh winter could again hamper major progress.


And the toll on civilians shows no signs of easing.


At least six people were killed and three injured in a Russian missile attack just after 3 a.m. on an apartment block in the city of Mykolaiv, about 55 miles west of Kherson city, local officials said.


"It's the next war crime of the Russian occupants, we have six victims and it's just civilians," Dmytro Pletenchuk, spokesperson for the Mykolaiv Regional Military Administration, told NBC News at the scene.


There have only been 45 days without any shelling in Mykolaiv since the war began, he said. Russia has consistently denied targeting civilians.


Ludmyla, 54, a kindergarten teacher who lives in the block of apartments that was shelled overnight, but spent the night in another part of the city, said: "I saw on the internet that the whole world saw that it was our house that got hit. We are fine, we are alive but it is very, very sad for the people who have died."


As the cleanup operation continued and the dead were carried away from the scene in body bags, residents salvaged what they could from their damaged homes, while a local charity handed out food and local children fed pigeons and played on swing sets.


Ukrainian President Volodymyr Zelenskyy said that the residential attack was a "cynical response" to Ukraine's success on the battlefield.


"Russia does not give up its despicable tactics. And we will not give up our struggle. The occupiers will be held to account for every crime against Ukraine and Ukrainians," he wrote on his Telegram channel.