Russian forces pressed on with a "counter-terrorism operation" in a border district on Tuesday, a regional governor said, a day after what appeared to be one of the biggest cross-border incursions from Ukraine since the war began 15 months ago.
Russia said on Monday it was battling an incursion by Ukrainian saboteurs who crossed into the Belgorod region. A Ukrainian presidential adviser said on Twitter the Kyiv government was watching the situation but "has nothing to do with it".
The Ukrainian outlet Hromadske cited Ukrainian military intelligence as saying two armed Russian opposition groups, the Liberty of Russia Legion and the Russian Volunteer Corps, both consisting of Russian citizens, were responsible for the attack.
The Russian regional governor, Vyacheslav Gladkov, said on the Telegram messaging service a "counter-terrorism operation" was still going on.
"The cleaning of the territory by the Ministry of Defence together with law enforcement agencies continues," Gladkov said.
On Monday, Gladkov said at least eight people had been wounded, several buildings damaged and many residents had left. He said he had restricted movements and communications.
Gladkov said two buildings were attacked by drones overnight and people could not return to their homes.
"I now appeal to the residents of the Graivoron district, who... temporarily left their homes, it is not possible to return yet," he said.
Gladkov said one woman died during the evacuation on Monday and there were reports of two people wounded. The "number one" task on Tuesday was to reach them, he said.
The Russia Volunteer Corps published video footage late on Monday showing what it said was a fighter inspecting a captured armoured vehicle. Another video showed what it said were fighters operating an armoured vehicle on a country road.
Other videos posted on Russian and Ukrainian social media channels showed pictures and video of what were described as captured Russian servicemen and their identity documents.
Reuters was not able to independently verify the situation.
Governer imposes 'counter-terrorist' measures
Kremlin spokesman Dmitry Peskov said Russian President Vladimir Putin had been informed and that work was under way to drive out the "saboteurs", the state-run RIA Novosti news agency reported.
The Telegram channel Baza, which has links to Russia's security services, said there were indications of fighting in three settlements along the main road into Russia. The "Open Belgorod" Telegram channel said power and water had been cut off to several villages.
The Liberty of Russia Legion said on Twitter it had "completely liberated" the border town of Kozinka. It said forward units had reached the district centre of Graivoron, further east.
"Moving on. Russia will be free!" it wrote.
Russia launched a full-scale invasion of Ukraine in February last year.
The Kremlin said the incursion by a "Ukrainian sabotage and reconnaissance group" was aimed at distracting attention from the eastern Ukrainian city of Bakhmut, which Russian forces say they captured in its entirety after more than nine months of fighting.
Russia says capturing Bakhmut opens the way to further advances in the eastern industrial region known as the Donbas. Ukraine says its advance on the Russian forces' flanks is more meaningful than its withdrawal from Bakhmut itself, and Russia would have to weaken its lines elsewhere to send reinforcements to hold the shattered city.
There were more than 30 clashes in the main sectors of the frontline with the epicentre of fighting remaining Bakhmut and Maryinka further south, the Ukrainian military said early on Tuesday.
"Battles for the city of Bakhmut continue,” it said.
Reuters could not independently verify the reports.