An explosion derailed a freight train in Russia’s Bryansk region on Monday, according to the local governor and the Russian railways company, the latest in a spate of apparent attacks to hit the area bordering Ukraine.
Photos and videos circulating on social media showed a large fire burning and a train tilted askew, with at least one carriage lying on its side.
The governor of the Bryansk region, Aleksandr V. Bogomaz, blamed an “unidentified explosive device,” saying in a post on the Telegram messaging app that there were no casualties. He did not say who was responsible, and Ukraine did not claim to have been behind the blast, although Kyiv generally maintains a policy of strategic ambiguity about strikes on Russian territory.
The Russian railways company said in a statement that “an intrusion by unauthorized individuals” derailed the train, which set the locomotive on fire. The incident blocked traffic on the rail line, the statement said.
In neighboring Belarus, the Ministry of Transport and Communications issued a statement saying that the blast involved one of its freight trains, the official Belta news agency reported. Eight cars of the 78-car train derailed, it said, but the locomotive crew was not injured.
Rybar, an influential pro-war Russian military blog that posted one of the videos, said on the Telegram messaging app that train cars carrying oil products and lumber were lying on their side.
The blast came a day after Mr. Bogomaz said four people in the region were killed by Ukrainian shelling from across the border.
Russia has used territories close to Ukraine — including the Bryansk region, along Ukraine’s northern border — to stage assaults, fire rockets, launch air assaults and mount other attacks throughout the 14-month-old war. The Ukrainian government has expressed growing concern that Moscow is using the Bryansk region to launch drone assaults.
Officials in Kyiv have said they reserve the right to strike targets within Russia that they claim are used to attack Ukrainian towns and cities, but have promised not to use weapons supplied by Western allies for such assaults, since allies fear Moscow could view that as a provocation.
In March, Ukrainian special forces said that they had destroyed an unmanned observation tower in Russia’s Bryansk region using a drone strike, a rare public acknowledgment of a cross-border attack that underscored Kyiv’s increasing willingness to directly strike Russian territory.
That came days after a brief armed incursion into a village in Bryansk by partisans claiming to fight for Ukraine, a rare raid inside Russia that prompted President Vladimir V. Putin to cancel a trip and convene an emergency meeting of his security council.
Marc Santora and Neil MacFarquhar contributed reporting.