Luhansk regional governor Serhiy Haidai told Ukraine TV that Saturday’s fire started when tons of oil leaked from damaged radiators at the nitrogen plant.
Hundreds of civilians are reportedly sheltering at the facility.
Severodonetsk is a city where Russia intensifies conflicts in eastern Ukraine.
Clashes have been going on for more than three months. While the Moscow administration’s efforts to seize the big cities, including the capital, Kyiv, were negative, instead it has been trying to seize the Luhansk and Donetsk regions for a while. These two regions are known as “Donbas”.
Capturing Severodonetsk and the nearby cities of Lysychansk is important for Russia as it will gain control over Luhansk.
Governor Haidai confirmed in his statement that the vast majority of Severodonetsk is now in Russian hands. The Russian army, on the other hand, said that all settlements in Severodonetsk are under their control.
In a statement on Saturday, Haidai said the “nitrogen plant has been under heavy bombardment for hours” but did not say whether there were any casualties or if the fire was later extinguished.
Ukrainian authorities estimate that as many as 800 civilians are hiding in underground bunkers at the Nitrogen plant.
Haidai described the current situation in Severodonetsk as “difficult but under control”:
“Our soldiers are winning street battles, but unfortunately, the enemy units are destroying the houses that our troops use as shelters, layer by layer. When we remove the enemy from a street, they begin to destroy house-to-house with their guns and tanks.”
Ukrainian President Volodymyr Zelensky also said that Russian troops suffered “very significant” losses in the Donbas.
Zelenskiy added that Ukrainian troops recaptured villages and towns in the southeastern regions of Kherson and Zaporizhzhia.
Ukraine, on the other hand, demands more weapons from its allies due to the large number of Russian artillery units.