The incident reportedly killed at least four soldiers and several civilians, including two teenage girls.
The clash is believed to have occurred last week in the village of Urzuf, located some 25 miles away from the occupied port city of Mariupol, between Chechen fighters loyal to the Kremlin, Kadyrovites, and Russian soldiers.
The Mariupol city council first reported the incident, sharing footage on its Telegram channel of what appears to be the aftermath of the shooting.
In the video can be seen the bodies of two men – one in uniform and one wearing civilian clothes – slumped in cars riddled with bullets.
It isn’t clear what brought the two factions of soldiers, both loyal to the Kremlin, to fight one another on Friday.
An adviser to the exiled mayor of Mariupol, Piotr Andryushenko, claimed the brawl happened as one Chechen soldier got drunk and opened fire on civilians and members of the Russian military, independent Russian outlet Meduza reported.
The adviser added Chechen security forces were “allowed to take leave in Urzuf” and that after the shooting nobody could enter or exit the city.
Mr Andryushenko also spoke about the reported incident, claiming, as reported by The Times: “They started tearing off each other’s shoulder straps and there was a shootout.”
The Moscow-installed head of the Mariupol region, Ivan Topuzov, also spoke of a shooting between the two pro-Kremlin sides.
Speaking to Astra, an independent channel on messaging platform Telegram, Mr Topuzov said Russian investigators had not provided him with any information.
He said: “When I got there, officials from the investigative committee were at work.
“They wouldn’t let me through and said, ‘It’s none of your business’. There are victims but I don’t know how many.”
On the other hand, senior Chechen official Ahmed Dudayev slammed reports that his fighters had been involved in the shootout as “disinformation”.
While he hit out the reports by the Ukrainian city council “cheap falsification”, he didn’t deny the incident taking place.
This isn’t the first report of infighting between pro-Kremlin.
Kherson residents said last year Chechen forces had clashed with mercenaries of the Wagner Group during their occupation of the region.