At least 13 people were killed, including a child, and 39 injured in a Ukrainian drone attack in the Russian republic of Tatarstan, authorities in the region said. It was one of the highest civilian death tolls in the country in recent months.

The head of Tatarstan, Rustam Minnikhanov, said the city of Nizhnekamsk, which is roughly 750 miles east of the Ukrainian border, came under a “massive” drone attack targeting industrial and civilian facilities on Monday morning. Russian media reported that the attacks hit a major oil refinery.

Ukrainian officials confirmed their military had struck the oil facility “as part of efforts to reduce the Russian aggressor’s military capabilities.” Ukraine has targeted Russian oil facilities with long-range drones almost daily in recent months in an attempt to reduce Russian oil refining capacity to put further pressure on the country’s fuel supply and economy.

Ukrainian President Volodymyr Zelenskyy says it is a campaign to try to force Russian President Vladimir Putin to the negotiating table and stop his more than four-year-old invasion.

“We do deliver entirely justified responses, and every Russian strike will be met with our response. Russia’s war will be felt more and more at their own home – in Russia,” Zelenskyy said late Sunday on social media. “The only reason this is still continuing is Russia’s unwillingness to end this war.”

Russia has also regularly battered Ukraine from the air using missiles, powerful glide bombs and drones, hitting civilian areas and causing thousands of civilian casualties, according to the United Nations.

The World Health Organization’s European office said Monday that one of its warehouses in the central Dnipro region of Ukraine had been struck twice in less than 24 hours.

The attacks destroyed emergency supplies worth an estimated $500,000 that were intended for front-line health facilities, it said in a statement.