An explosion rocked the Russian-occupied city of Melitopol early on Monday, sending plumes of smoke into the sky just outside the office of the pro-Kremlin head of the region, according to Ukrainian and Russian officials.
It was unclear who was responsible for the blast, which both Ukrainian and Russian officials said appeared to target the proxy leader of the region, Yevgeny Balitsky. If Ukrainian partisans were behind the explosion, it would be one of the most brazen acts of insurgency since Russian forces occupied the southern Ukrainian city in the early days of the war.
The former mayor of Melitopol, Ivan Federov, who was himself abducted by Russian forces and later freed in a prisoner exchange before ending up in exile, said that people he was in contact with still in the city were trying to determine whether anyone was injured in the attack and who might have directed it.
Pro-Kremlin authorities in the city blamed Ukrainian partisans for the explosion, which they said had injured two people.
“This morning there was a terrorist attack aimed at destabilizing the peaceful life of the city,” Melitopol’s Russia-installed authorities said in a statement on Telegram. According to the statement, a car packed with explosives exploded in the city center at 7:40 a.m., injuring two “humanitarian aid” volunteers, a 28-year-old woman and a 25-year-old man.
“The Ukrainian government continues its war on the civilian population and the infrastructure of cities,” the statement said, adding that an investigation was underway.
Russia’s Investigative Committee, the equivalent of the F.B.I., also issued a statement saying that it would look into the explosion, which it blamed on “Ukrainian saboteurs” and said had gone off while humanitarian aid was being distributed. It said three people were injured, including two volunteers who were hospitalized.
A video still released by the Ukrainian President’s Office People showed people protesting the abduction of Mayor Ivan Fedorov, outside the Melitopol regional administration building in March.
It was not possible to independently verify the details of the attack.
Mr. Federov, the former mayor, said that whoever was responsible for the blast, the attack underscored the level of local opposition that Russia would continue to face.
“The ground will burn” in Melitopol, he said, until Russians “leave the city.”
The attack comes as the Ukrainian military is engaged in a counteroffensive to reclaim territory in the neighboring region of Kherson.
Large swaths of the provinces of Kherson and Zaporizka — where Melitopol is the second-largest city — were taken by Russian forces early in the war. While major towns and cities in the region were spared the widespread devastation wrought on population centers in northern and eastern Ukraine, the Russian occupation has grown more repressive with time, according to witnesses who have fled.
There are no precise estimates of the population remaining in Russian-controlled territory across the two regions, and the path to escape has grown increasingly treacherous. Ukrainian officials estimate that only about half of the peacetime population remains — which could mean more than one million people.
As reports grow of Russian soldiers kidnapping local officials and other potential threats to the Russian occupation, there has been a corresponding rise in reports of partisan violence.
Serhii Kuzan, head of the Ukrainian Center for Security and Cooperation, which specializes in military analytics, told Radio Liberty on Friday that the resistance movement in the occupied territories had grown and, while largely autonomous, was supported by the state.
“It all started with hundreds of informants. Now it is thousands and thousands of people in each area who perform a completely different range of actions, ranging from informing our defense forces about the movement of enemy equipment, enemy personnel, including leadership, the movement of patrols and more,” he said.
He said partisans were attacking Russian warehouses and Russian patrols as well as targeting “the top leadership of the occupying forces, even the general staff as well, and of course collaborators.”
Those claims were impossible to independently verify.