A series of explosions have rocked Crimea after a reported Ukrainian drone attack on the peninsula, which was annexed by Russia in 2014.
A video posted online shows an alleged explosion near a fuel depot in the southeastern city of Feodosia.
Russian officials announced that 38 drones had been shot down. Kerch Bridge, which connects Crimea and Russia, has been temporarily closed.
The attack comes as Ukraine continues to call on its allies to increase arms supplies.
Russian forces have recently been gaining strength in Ukraine as Kiev struggles to maintain its military with Western-made weapons. Last month, Moscow captured the main eastern city of Avdiivka.
But British military intelligence says this comes at a heavy price. The latest update said February was Russia's deadliest month since the full-scale invasion began on February 24, 2022, with 983 casualties per day.
“Today, Russia has very likely lost more than 355,000 killed and wounded personnel during the Ukraine war,” the newspaper said. It is not clear how this number was reached.
Russia does not release casualty records. A few days ago, Ukrainian President Volodymyr Zelenskiy said that since February 2022, Ukraine has lost 31,000 troops.
Russia has not reported any damage from the latest attacks in Crimea, but witnesses have reported windows shaking and car alarms going off. Kiev has not acknowledged its military involvement.
On Saturday, a Russian drone struck an apartment complex in the Ukrainian city of Odesa, killing at least 10 people, including three young children.
On Sunday, Russia targeted the southern Kherson region, killing one person and wounding three, Ukrainian officials said.
Russia's military has launched thousands of Iranian-made drones at Ukrainian targets since it invaded the country more than two years ago.
In retaliation, Ukraine targeted Russian facilities, particularly oil facilities.
A drone crashed into a house in St. Petersburg, Russia's second largest city, on Saturday. Approximately 100 people were evacuated, but there were no reports of casualties.
Crimea, with its air bases, military concentrations, training grounds and Black Sea fleet, is a key target for the Ukrainians.
At one point last year, it was thought that they were planning to launch a full-scale offensive to retake the peninsula.
In particular, Ukraine has repeatedly attacked Russia's Black Sea Fleet. Satellite images from last year showed many Crimea-based warships leaving the peninsula for Russia's Black Sea port of Novorossiysk.
Last month, the Russian amphibious ship Caesar Kunikov sank off the coast of Crimea, according to the Ukrainian military.
The sister ship Novocherkassk was collided in December last year while in port in Feodosia.
Last September, in one of the largest attacks on the Black Sea Fleet, Ukraine used up to 10 missiles and three unmanned boats to attack naval targets and port infrastructure. A huge fire broke out at the shipyard in Sevastopol.
Ukraine has also repeatedly targeted the Kerch Bridge, a key supply route for Russian forces occupying parts of the country's south.
Kiev has repeatedly said it plans to retake Crimea and all Russian-occupied territory.
Ukraine relies heavily on arms supplies from the United States and other Western allies to continue fighting Russia, a much larger military with extensive weapons and artillery.
Ukraine's military is running low on ammunition as former President Donald Trump's allies in Congress refuse to approve a $61bn (about £4.8tn) military aid plan.