At least 12 people were killed and 39 others injured in a Ukrainian drone attack on industrial and civilian targets in Nizhnekamsk, a city in Russia’s Tatarstan region that is home to a major oil refinery, Mayor Radmir Belyayev said on Monday.The region’s oil refinery, one of Russia’s most technologically advanced facilities, was also hit in the attack, according to Russian media reports.Tatarstan head Rustam Minnikhanov has declared a period of mourning following the Ukrainian attack, Mayor Belyayev said, as cited by Reuters.Tatneft’s TANECO refinery, which was also targeted by Ukraine in early June, processed 17 million tonnes of crude oil in 2024, producing 2.7 million tonnes of gasoline and 8.5 million tonnes of diesel fuel.Ukraine has intensified its strikes on Russian oil refineries in recent months as part of a campaign that has caused fuel shortages in several parts of Russia. Authorities have said most of the initial shortages have since been resolved.