The RIA news agency said that two assailants opened fire on a group of volunteers who wished to fight in Ukraine on a Russian military training ground on Saturday, killing at least 11 people and wounding 15 others.

A "terrorist" attack by two nationals of former Soviet nations opened fire on a military site in the Belgorod region bordering Ukraine, and "both were killed in retaliatory fire," according to Russian news media citing the defense ministry on Saturday.

During a firearms training exercise, the terrorists fired small arms at the unit's employees, according to a defense ministry statement reported by RIA.

Meanwhile, Ukrainian President Volodymyr Zelensky stated on Saturday that the situation near the eastern town of Bakhmut was "extremely difficult," days after pro-Russian forces announced they were moving closer to the city.

"A very severe situation persists in the Donetsk and Luhansk regions" in the Donbas, Zelensky stated in his daily speech, adding that "the most difficult situation persists near Bakhmut, as it has for the past few days." We continue to maintain our positions."

This comes after separatist fighters supported by Russia in the Donetsk area of Ukraine announced on Thursday that they had captured two neighboring settlements, Opytine and Ivangrad.

In an attempt to capture the 70,000-person-strong city of Bakhmut, Russian forces have been bombarding it for weeks.