KYIV, Ukraine — Ukrainian and Russian forces traded fire on Monday from across the broad expanse of the Dnipro River that now divides them after Russia’s retreat from the southern city of Kherson, reshaping the battlefield with a victory that Ukraine’s president, Volodymyr Zelensky, declared marked “the beginning of the end of the war.”
The Dnipro has become the new front line in southern Ukraine, and officials there warned of continued danger from fighting in regions that have already endured months of Russian occupation.
Through the afternoon, artillery fire picked up in a southern district of the city near the destroyed Antonivsky Bridge over the Dnipro, stoking fears that the Russian Army would retaliate for the loss of the city with a bombardment from its new positions on the eastern bank.
Mortar shells struck near the bridge, sending up puffs of smoke. Near the riverfront, incoming rounds rang out with thunderous, metallic booms. It was not immediately possible to assess what had been hit.
The head of the Kherson regional military administration, Yaroslav Yanushevich, urged the tens of thousands of remaining residents in the city to evacuate while Ukrainian forces worked to clear land mines, hunt down Russian soldiers left behind and restore essential services.
The mines are a significant danger. Four people, including an 11-year-old, were killed when a family driving in the village of Novoraysk, outside the city, ran over a mine, Mr. Yanushevich said. Another mine injured six railway workers who were trying to restore service after lines were damaged. And there were at least four more children reportedly injured by mines across the region, Ukrainian officials said in statements.
The deaths underscored the threats still remaining on the ground, even as Mr. Zelensky made a surprise visit to Kherson, a tangible sign of Ukraine’s soaring morale.
“We are, step by step, coming to all of our country,” Mr. Zelensky said in a short appearance in the city’s main square on Monday, as hundreds of jubilant residents celebrated.
Russian forces continued to fire from across the river on towns and villages newly recaptured by Ukrainian forces, according to the Ukrainian military’s southern command. Two Russian missiles struck the town of Beryslav, which is just north of a critical dam, the military said. It was not immediately known if there were any casualties.
The Ukrainian government is setting up evacuation routes to the cities of Mykolaiv and Kryvyi Rih, said Iryna Vereshchuk, a Ukrainian deputy prime minister. “We will not have time to restore power supplies enough to heat homes where children, the sick and people with reduced mobility live,” she said. “It will not be a mass evacuation. It will cover those who are sick, the elderly and those left without care of their relatives.”
Residents on the Dnipro’s eastern bank described an increasingly repressive environment as Russian soldiers poured into the area.
“Occupants rob local people and exchange stuff for samogon,” or homemade vodka, said one resident, Tatiana, who communicated via a secure messaging app from Oleshky, a town across the river from Kherson City. “Then they get drunk and even more aggressive. We are so scared here.” She asked that her surname be withheld for security.
Other residents on the eastern bank offered similar accounts of disorder and chaos.
“Russians roam around, identify the empty houses and settle there,” Ivan, 45, wrote in a text message. He lives in Skadovsk, which is south of Kherson city, and asked that his surname not be used out of concern for his safety. “We try to connect with the owners and to arrange for someone local to stay in their place. So that it is not abandoned and Russians don’t take it.”
Throughout the weekend, the Ukrainian military sought to target Russian forces as they tried to regroup after their retreat from Kherson. The Ukrainian air force launched strikes on the east side of the river, with the Ukrainian military saying it had fired on 33 Russian positions.
Andrew E. Kramer and Anna Lukinova contributed reporting.