Officials in Belgorod, a Russian city near Kharkiv, Ukraine, say Ukrainian military helicopters were responsible for explosions and subsequent fires at a fuel depot early Friday. “The fire at the oil depot occurred as a result of an airstrike coming from two helicopters of the Ukrainian Armed Forces, which entered the territory of the Russian Federation flying at a low altitude,” Belgorod regional governor Vyacheslav Gladkov wrote on Telegram. “There are no victims,” though two workers were injured.

Ukraine has not claimed responsibility for the explosions; Bohdan Senyk, the head of the public affairs department of the Armed Forces of Ukraine, told CNN there was “no information” about the incident. “It would be the first time that Ukrainian aircraft have flown into Russian airspace to hit a target. bringing the war home to Russia” and giving “a huge boost to the morale of Ukraine’s military,” BBC defense correspondent Jonathan Beale writes from Odessa. 

“Ukrainian helicopter pilots have plenty of experience of flying low and fast to avoid being detected by military radar and air defence systems. They’ve been doing exactly that in the Donbas region in eastern Ukraine for years,” Beale adds. “But if these unconfirmed reports are correct — flying at night, well into Russian territory, to launch an attack on an enemy fuel depot would have required extraordinary bravery — as well as finely honed flying skills.”

The Kremlin said the strikes on the fuel depot do not create comfortable conditions to continue peace talks, Russian President Vladimir Putin has been informed, and everything is being done to reorganize the fuel supply chain. Russia has hit several Ukrainian fuel depots throughout the country, claiming the purpose is to cut off supply to Ukraine’s military.

“The Belgorod area was used as a staging ground for Russian forces shortly before the invasion, and Kharkiv has since been relentlessly shelled and hit with missiles,” CNN reports. There were several explosions reported at an ammunition depot near Belgorod late Tuesday night, and Gladkov said Wednesday that a preliminary investigation pointed to a fire sparking those blasts.