A Russian town comes under military attack. The Russian government blames Ukrainian "saboteurs". Ukraine says the attackers are anti-Putin guerillas.
Here's what we know about the fighting in Belgorod.
What’s happening in the Belgorod region?
On Monday night fighting broke out near the Russia/Ukraine border, leaving two people in hospital after a village was shelled, according to Russian media via Reuters.
The fighting happened in the Belgorod region, 40 kilometres east of the border about an hour away from the Ukrainian city Kharkiv.
Parts of the region have come under drone attack since Moscow invaded Ukraine last year.
The region’s governor Vyacheslav Gladkov initially said the attack damaged several houses and administrative buildings.
On Tuesday he said a "counter-terrorism operation" in the region was ongoing, with troops and law enforcement agencies continuing "to clean up" the territory on the border with Ukraine.
Who is Russia blaming?
Mr Gladkov blamed the attack on what he said was a sabotage group from Ukraine.
Kremlin spokesperson Dmitry Peskov said the action was an attempt by Ukrainian saboteurs to divert attention from the city of Bakhmut, which Moscow claims to have captured after a months-long battle which has claimed thousands of lives.
Mr Peskov said Russian President Vladimir Putin had been informed and work was underway to drive out the saboteurs.
An effort had begun to "push them out and liquidate them," he said.
Belgorod's governor has imposed a "counterterrorism regime" giving authorities more power to clamp down on people's movements and communication.
What is Ukraine saying?
Ukrainian officials insist they have nothing to do with the attack, but say they are monitoring the situation.
"Ukraine is watching the events in the Belgorod region of Russia with interest and studying the situation, but it has nothing to do with it," presidential adviser Mykhailo Podolyak tweeted.
"As you know, tanks are sold at any Russian military store, and underground guerilla groups are composed of Russian citizens."
Mr Podolyak said Ukraine's military operated only on Ukrainian territory, and echoed Ukrainian military intelligence in blaming Russian partisans for the incursion.
"The only driving political force in a totalitarian country of tightened screws is always an armed guerilla movement," he said.
Has anyone claimed responsibility?
In a Telegram post, groups calling themselves the Freedom of Russia Legion and Russian Volunteer Corps claimed responsibility.
The Freedom of Russia Legion describes itself as an anti-Kremlin militia group working to liberate Russia from Vladimir Putin.
The Russian Volunteer Corps is made up of far-right, anti-Putin Russians who claim to be fighting on the side of Ukraine, according to the Associated Press news agency.
What else do we know about the fighting?
The Legion said it had "completely liberated" the border town of Kozinka and was pushing further into Russian territory.
Video footage posted on social media channels linked to the two supposed partisan groups showed what was alleged to be a fighter inspecting a captured Russian armoured vehicle.
Another video showed what it said were fighters driving an armoured vehicle on a country road inside Russian territory.
On Tuesday Mr Gladkov appeared to admit that some residents had been forced to flee 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.
Mr Gladkov said one woman died during the evacuation on Monday and reportedly two people were wounded but Russian security forces had not been able to reach them.
ABC/wires
