At least 13 people, including children, were killed and 39 others injured in a Ukrainian drone strike on Nizhnekamsk in Russia’s Tatarstan region, Russian officials said. Reuters reported the information on Monday, citing Russian officials. Ukrainian military authorities said the strike targeted Tatneft’s Taneko oil refinery in Tatarstan, about 800 kilometres east of Moscow. Local authorities described it as one of the largest recent attacks in Russia in terms of civilian casualties.

A fire spread at the refinery after the attack, while videos circulating on social media showed thick smoke rising above the facility. Russian investigators opened a criminal investigation, calling the incident a terrorist act. They alleged that Ukrainian forces had also targeted residential areas. Nizhnekamsk’s mayor said in a Telegram message that Tatarstan leader Rustam Minnikhanov expressed condolences over the deaths.

The Taneko refinery had previously been hit by a Ukrainian drone attack in early June. The report said Ukraine has been striking oil refineries and energy infrastructure across Russia for months to increase pressure on its energy sector, creating fuel-supply strain in some Russian regions. Russia and Ukraine both deny intentionally targeting civilians.