Reports say Aleksei Mozgovoi, a leading pro-Russian separatist commander in eastern Ukraine, has been killed along with at least six other rebels in an attack by an unknown group.
A press service for territory in Ukraine's Luhansk region controlled by separatists said on May 23 that Mozgovoi, the leader of the rebels' Ghost battalion, was killed when his car blew up and was then ambushed by attackers who sprayed it with machine-gun fire.
Sergei Gorenko, a spokesman for the separatists, said "at the moment, one theory is that it was the work of a raiding group," but did not give any further details.
TASS on May 24 reported that Oleksandr Hladkyy, described by the Russian news agency as the head of a Ukrainian commando unit known as the Shadows, had claimed responsibility for the attack on his Facebook page.
The incident occurred near the rebel-controlled town of Alchevsk, about 30 kilometers away from the frontline.
None of the others killed in the attack were named.
There have been several assassination attempts against the hard-line Mozgovoi, most recently in March.