Russian missile strikes in the southern city of Zaporizhzha have left one person dead and five others wounded, Ukrainian officials said.
Meanwhile, officials in the Russian-controlled city of Donetsk said Ukrainian shelling has killed at least five people.
It is a reminder that hostilities have not diminished despite a high-profile prisoner swap just hours earlier.
Zaporizhzhia governor Oleksandr Starukh said Russian forces targeted infrastructure facilities and damaged nearby apartment buildings.
Kyrylo Tymoshenko, the deputy of the Ukrainian president’s office, said a hotel in the central part of the city was struck and rescuers were on the scene trying to free people trapped in the rubble.
The Zaporizhzhia region is one of four in which Russia is planning to hold referendums starting on Friday on becoming part of Russia, but the city itself is in Ukrainian hands.
Meanwhile, Donetsk city mayor Alexei Kulemzin said at least five people were killed when Ukrainian shelling on Thursday hit a covered market and a passenger minibus.
Just hours before the latest attacks, a high-profile prisoner swap saw 215 Ukrainian and foreign fighters exchanged — 200 of them for a single person, an ally of Russian President Vladimir Putin.
Among the freed fighters were Ukrainian defenders of a steel plant in Mariupol during a long Russian siege and 10 foreigners, including five British nationals and two US military veterans who had fought with Ukrainian forces.
A video on the BBC news website on Thursday showed two of the released British men, Aiden Aslin and Shaun Pinner, speaking on a plane.
It said they had arrived in Riyadh, Saudi Arabia.
“We just want to let everyone know that we’re now out of the danger zone and we’re on our way home to our families,” Mr Aslin said in the video, as Mr Pinner added: “By the skin of our teeth.”
The speed with which the Russian missile attack came after the swap suggested that the Kremlin was seeking to dispel any notion of weakness or waning determination to achieve its war aims following recent battlefield losses and setbacks that gravely undercut the aura of Russian military might.
Those losses culminated on Wednesday in Mr Putin’s order for a partial mobilisation of reservists to bolster his forces in Ukraine that sparked rare protests in the Russia and was derided in the West as an act of weakness and desperation.
The partial call-up was short on details, raising concerns of a wider draft that sent some Russians scrambling to buy plane tickets to flee the country.
The move preceded referendums that authorities in Russian-controlled regions in eastern and southern Ukraine are preparing to hold on becoming part of Russia — a move that could allow Moscow to escalate the war.
The votes start on Friday in the Luhansk, Kherson and partly Russian-controlled Zaporizhzhia and Donetsk regions.
Foreign leaders are already calling the votes illegitimate and non-binding.
Ukrainian President Volodymyr Zelensky said they were a “sham” and “noise” to distract the public.
