Serhiy Haidai, the head of the Luhansk Regional State Administration, announced a new attack by the invaders. He urged people not to leave the shelters and close the windows if they are at home.

Read more: More than 4.4m Ukrainian refugees have fled the country – UN

Serhiy Haidai stressed that nitric acid is dangerous for the human body. Therefore, the head of the regional military administration asks to prepare masks soaked in a soda solution.

"Nitric acid is dangerous if inhaled, swallowed and in contact with skin and mucous membranes. Acid fumes are irritating to the respiratory tract. At a weak poisoning level, there are signs of bronchitis, easy bronchiolitis, dizziness, and drowsiness; at a severe poisoning level - pulmonary oedema. Gas masks are used to protect against nitric acid vapours and mists," - said Gaidai.