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, or debris, appear to have caused extensive damage. Unverified images circulating show explosions and huge clouds of smoke around the city, which is located in Tatarstan, about 500 kilometres east of Moscow.
The attack appears to have targeted an oil refinery.
Extensive Russian attacks in Ukraine were also reported during the day on Monday. According to Ukrainian authorities, at least five civilians have been killed in the Kharkiv region.
