KYIV, Ukraine — Ukrainian residents took to the streets of Kherson on Friday to unfurl their national flag outside government buildings, Ukrainian officials said, as Russian forces scrambled to escape to more secure territory across the Dnipro River and Ukrainian forces continued to advanced on the key southern city, according to residents and Ukraine’s military.
Russia’s Defense Ministry said in a statement that the retreat of all troops to the eastern bank of the Dnipro River was complete. However, residents of Kherson said on Friday morning that some Russian soldiers were still present in the city, dressed in civilian clothes.
That did not stop people from going to government buildings in a show of defiance as they waited for the Ukrainian military to enter the city in force.
“The people of Kherson are waiting,” Ukraine’s Parliament said in a post on the Telegram messaging app alongside a photograph showing people with Ukrainian flags in front of the regional administration building. “Moment for the future history books!”
Photographs shared with The New York Times by residents showed several dozen people outside the main government building waving flags and wrapping the base of a statue outside the building in blue and gold.
The dramatic scenes in Kherson came less than 48 hours after Russia’s defense minister announced that Russian troops in the city would withdraw. After ordering all civilians to leave towns and villages in the region last month and engaging in a systematic effort to loot museums, government building, hospitals and homes, Russian forces this week blew up bridges and laid a vast network of mines to slow the Ukrainian advance as they abandoned long-held defensive positions west of Kherson city.
Even as its soldiers fled, the Kremlin said that it still considered Kherson — which President Vladimir V. Putin illegally annexed in September — to be a part of Russia.
“This is a Russian region,” Dmitri S. Peskov, the Kremlin’s spokesman, told reporters on Friday. “It has been legally fixed and defined. There can be no changes here.”
As he spoke, Ukrainian soldiers continued to move through towns and villages in the region, greeted joyously by tearful residents who had endured nine months of occupation.
The remaining residents of Kherson, though, were still awaiting the arrival of Ukrainian troops.
One resident, Ivan, said on Friday that the sound of artillery had thundered across the city through the night and into the early morning. He said much of the fire seemed to be directed at Russian convoys trying to move across the Antonivsky bridge, the main crossing out of the city.
Before dawn, he said, a huge explosion was heard in the area of the bridge.
“It was very foggy in the morning and we couldn’t see much, but people from Antonivka say that the roofs of the houses were taken away by the explosion wave,” Ivan said in a text message.
Videos and photographs posted to social media showed the destruction of the bridge and Rybar, an unofficial but influential pro-war Russian military blog, reported that retreating Russian forces had destroyed it at 5 a.m., posting a video that it said showed the strike that brought it down.
The apparent destruction of the bridge left any Russians remaining in the city with only an ad hoc network of ferries and pontoon bridges across the river. The other major crossing is 50 miles to the north, at the Kakhovka dam.
The Antonivsky bridge has been under Ukrainian fire for months as they used long-range missiles to damage the span and limit the ability of the Russians to resupply their forces. But the Ukrainian military had been careful not to destroy it, apparently wanting to preserve it to chase departing Russian forces.
Ivan, who provided only his first name for security reasons, said that there were few people left in the city of Kherson and that Russians could still be seen operating in the northern and central parts of the city. Four more residents offered similar accounts of Russians in civilian clothes moving about the city.
Ukrainian officials have warned that Russia may have left a contingent of soldiers behind disguised as civilians to engage the Ukrainians in street battles or stage sabotage operations.
“Enemy troops are hastily packing into boats that appear suitable for crossing and trying to escape,” the Ukrainian military said on Friday morning.
It said that the Russians were setting up defensive positions on the eastern bank of the Dnipro and shelling the advancing Ukrainians across the river. It was not immediately possible to independently verify the claim.
Anna Lukinova and Ivan Nechepurenko contributed reporting.