Footage has emerged of Russian tourists running in fear as an explosion sends a mushroom cloud into the air during a suspected attack on a Russian air base.
Analysts suggest the blasts could indicate a significant escalation in the war in Ukraine.
Families holidaying on beaches are seen scurrying away from the scene to find cover near the Russian Saky military base in Novofedorivka on the western coast of Russia-occupied Crimea.
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Other tourists are seen watching the clouds of smoke rise in the distance.
The footage also shows burnt-out cars that appear to have been damaged in the blasts on Tuesday, close to the air base.
While the cause of the blasts has yet to be fully established, there is speculation they were the result of an attack by Ukrainian forces, although Ukrainian officials have stopped short of publicly claiming responsibility.
One person was reportedly killed and others wounded by the powerful blasts, which Moscow had claimed were just part of a Russian operation to blow up ammunition stores.
However, Ukraine's air force said nine Russian jets were destroyed in the explosions, despite Russia denying that any aircraft were damaged, or that any attack took place.
The explosions would represent a significant increase in the intensity of the war if it were established that Ukrainian forces had carried out an attack on Russian-occupied territory.
Ukrainian officials may not have claimed responsibility for the attacks but they have poked fun at Russia's explanation that munitions at the Saki air base caught fire and blew up and underscored the importance of the peninsula that Moscow annexed eight years ago.
In his nightly video address several hours after the blasts, Ukrainian President Volodymyr Zelensky vowed to retake the peninsula, saying "this Russian war against Ukraine and against all of free Europe began with Crimea and must end with Crimea — its liberation".
Today, Wednesday, Russian authorities sought to downplay the explosions, saying all hotels and beaches were unaffected on the peninsula, which is a popular tourist destination for many Russians.
The fireballs sent tourists fleeing in panic as plumes of smoke towered over the nearby coastline.
They smashed windows and caused other damage in some apartment buildings.
Russian jets have used Saki to strike areas in Ukraine's south on short notice, and Ukrainian social networks were abuzz with speculation that Ukrainian-fired long-range missiles hit the base.
Officials in Moscow have long warned Ukraine that any attack on Crimea would trigger massive retaliation, including strikes on "decision-making centres" in Kyiv.
A Ukrainian presidential adviser, Oleksiy Arestovych, who is more outspoken than other officials, cryptically said on Tuesday the blasts were caused either by a Ukrainian-made long-range weapon or were the work of guerrillas operating in Crimea.
Watch: Why Ukraine wants more HIMARS weapons.
The base on the Black Sea peninsula that dangles off southern Ukraine is at least 125 miles away from the closest Ukrainian position — out of the range of the missiles supplied by the US for use in the HIMARS systems.
The Ukrainian military has successfully used those missiles, with a range of 50 miles, to target ammunition and fuel depots, strategic bridges and other key targets in Russia-occupied territories.
HIMARS could also fire longer-range rockets, with a range of up to about 185 miles, that Ukraine has asked for.
US authorities have refrained from providing them to date, fearing it could provoke Russia and widen the conflict.
The explosions in Saki have, however, raised speculation on social media that Ukraine might have finally got the weapons.
Ukrainian military analyst Oleh Zhdanov said the Ukrainian forces could have struck the Russian air base with a Ukrainian Neptune anti-ship missile that has a range of about 125 miles and could have been adapted for use against ground targets and fired from Ukrainian positions near Mykolaiv northwest of Crimea.
The Ukrainian military might also have used Western-supplied Harpoon anti-ship missiles that can also be used against ground targets and have a range of about 185 miles, he said.
"(Officially) Kyiv has kept mum about it, but unofficially the military acknowledges that it was a Ukrainian strike," Mr Zhdanov said.
If Ukrainian forces were, in fact, responsible for the blasts, it would be the first known major attack on a Russian military site in Crimea, which the Kremlin annexed in 2014.