MOSCOW — Dozens of armed men occupied the center of the city of Luhansk in eastern Ukraine on Wednesday, blocking the entrances to several government buildings during a standoff between two top officials in the Russian-backed separatist enclave.

Armored vehicles appeared on the streets and the city’s inhabitants were fleeing the area en masse, according to local news media reports.

The menacing deadlock in the so-called Luhansk People’s Republic began on Monday, after the interior minister refused to step down after being dismissed by the prime minister for what was called illegal activity.

Both breakaway republics in eastern Ukraine — Donetsk and Luhansk — have been plagued by murderous rivalries from the start of the conflict there in 2014, with factions vying for political control, financial gain and Moscow’s blessing.