Explosions were reported in Russian-occupied Luhansk in the evening of May 27 as Moscow-installed head of the region Leonid Pasechnik claimed a missile attack on the city.
Telegram channels shared photos and videos showing a major fire in Luhansk.
It broke out near the infrastructure facilities of the former Luhansk Higher Military Aviation School and the nearby aircraft repair plant, Luhansk Oblast Governor Artem Lysohor said.
Russia's Pasechnik said that information on damage and casualties "is being clarified."
The Kyiv Independent could not verify these claims. The Ukrainian military has not yet commented on the reports.
Ukraine targeted a Russian military base in Luhansk's suburb of Yuvileine on May 20, Lysohor said.
A week before, a Russian ammunition depot reportedly exploded in the occupied town of Sorokine (Krasnodon) in Luhansk Oblast.
Russia had occupied Luhansk and a significant part of the region since the start of its war in 2014.