"A drone was shot down near the MNPZ. There are no damages or casualties, there is no threat to MNPZ operation," he said on Telegram.
A total of nine drones that tried to attack Moscow were shot down by Sunday morning, Sobyanin added.
The drone that was shot down over the Moscow refinery fell on a free-standing utility building at the MNPZ compound, causing a fire. Firefighter were sent to the site. The blaze was taken under control hours later.
"After Moscow firefighters arrived at the site, the fire was promptly taken under control. There is no threat to the workers or the operations of the plant. The situation is calm. There is no open fire. Media reports to the contrary are false," the Russian Emergency Ministry said in a statement.
As many as 158 Ukrainian drones were intercepted by air defenses across Russian regions overnight.
Russian officials repeatedly slammed Ukrainian attacks on civilian infrastructure.