Black smoke blanketed the skies of southern Moscow on Thursday morning after Ukrainian drones struck and set fire to a major oil refinery, in what was the largest-ever attack on the Russian capital since the start of the war.

Moscow Mayor Sergei Sobyanin said around 6 a.m. local time that air defense systems were “repelling a large-scale attack” and that “several drones” managed to strike the Gazprom Neft-operated refinery located about 15 kilometers (9.3 miles) southeast of central Moscow.

Videos shared on social media showed huge columns of smoke and multiple large fires rising from the facility, which supplies around a third of Moscow’s gasoline and fuel. The refinery was also attacked on Tuesday, after which it reportedly halted operations.

“I woke up at 5 a.m. because I could hear drones being shot down. I felt horrified, shocked and angry. The closer this situation gets to us, the more I find myself thinking about human lives,” a woman who lives in southeastern Moscow told The Moscow Times, speaking on condition of anonymity.

Another resident, who lives near the Sadovod market in southeastern Moscow that was struck in Thursday's attack, said she did not hear the strikes but could see a fire at the market from her window. At the same time, she said many Muscovites have gotten used to drone attacks on the capital.