The attack was part of a broad Ukrainian drone offensive on Monday night. According to pro-regime Russian media, around 460 Ukrainian drones were shot down.
But in Nizhnekamsk, the drones appear to have caused significant damage. Unverified images circulating show explosions and huge clouds of smoke around the city, which is located in Tatarstan, around 500 kilometers east of Moscow.
According to news agencies, Ukraine's General Staff said it had struck the Taneko refinery, which belongs to the oil giant Tatneft.
Russian attacks in Ukraine were also reported on Monday. At least five civilians have been killed in the Kharkiv region, according to Ukrainian authorities.
