An early Friday drone strike triggered a major fire at the Ryazan Oil Refinery, one of Russia's largest fuel production facilities, according to local residents and Russian monitoring channels.

Residents reported multiple loud explosions after drones were seen flying over the city, with videos circulating online showing flames and thick smoke rising from the refinery.

"An ASTRA OSINT analyst has determined that in addition to two high-rise buildings, an oil refinery in the city was damaged. Photos taken by witnesses were taken near the Olympic Town microdistrict, approximately 4 km from the Ryazan Oil Refinery," one independent Russian outlet wrote.

Two high-rise buildings in Ryazan were also struck, resulting in significant casualties:

A Ukrainian drone barrage killed at least four people and ignited a huge fire at an oil refinery in the city of Ryazan on Friday, in what appeared to be a direct retaliation for a deadly Russian strike on Kyiv a day earlier.

Ryazan region Governor Pavel Malkov confirmed the deaths in posts on Telegram, adding that dozens of people, including children, were wounded in the attack. He said drones struck two apartment buildings and an industrial site, which he did not identify by name.

There were also reports that "black rain" fell from the sky after the refinery was struck, which adds additional confirmation to serious damage at the fuel facility amid the ongoing emergency response:

The strike sparked a fire at the Ryazan oil refinery, leading to what some locals described as an "oil rain." Residents complained online of sticky black spots on their cars, windows, and building facades. 

Ukrainian sources have alleged that both the Ryazan refinery and Gazprom's Astrakhan gas plant are considered critical components of Moscow's war infrastructure.

Last week a brief ceasefire held. Soon on the heels of the successful 3-day and US-backed 'V-Day' ceasefire between Russia and Ukraine, Russian forces went on to unleash several days of drone and missile barrages on Ukrainian cities, especially the capital. Some 1,500 missiles and drones were launched in just 48 hours.

BBC reported Thursday that "At least seven people have been killed, including a 12-year-old girl, in Kyiv after Russia launched a massive wave of drone and missile strikes on the Ukrainian capital and other regions, officials have said."

Sadly, the tit-for-tat 'revenge' strikes are only increasing, and more and more apartment blocks and civilian neighborhoods on each side have been coming under devastating attacks.