In a defiant last stand, a group of Ukrainian border guards told the Russian military to "go f*** yourself" before they were killed as they defended a small island in the Black Sea.
The 13 guards defending Zmiinyi 'Snake' Island, were among 137 civilians and military personnel killed in Thursday's attacks, according to Ukrainian president Volodymyr Zelensky.
In an audio clip circulating online, troops on an approaching Russian warship are heard to order Ukrainian guards on the island to "lay down your arms immediately to avoid bloodshed and unjustified deaths", but the guards on the island reject the demand.
A Russian officer is heard to say: "This is a military warship. This is a Russian military warship", warning if they did not surrender, "you will be bombed".
After a brief discussion among themselves, a guard is heard turning up the volume on the dial before responding by saying: "Russian warship, go f*** yourself."
Ukraine lost contact with its forces defending the island on Thursday after Russia conducted strikes from the air and sea, officials in Kyiv said.
The recording of the exchange between Ukrainian and Russian forces has been circulated by a Ukrainian official and the media outlet Ukrainskaya Pravda before being shared with millions on Twitter.
Anton Herashchenko, an adviser to the Ukraine interior minister, shared the clip on his Facebook page and said a Russian ship fired missile artillery after border guards refused to surrender.
President Zelensky confirmed that all border guards on the Zmiinyi island in the Odesa region had been killed on Thursday.
He said: "All border guards died heroically but did not give up. They will be awarded the title of Hero of Ukraine posthumously."
In a video address, he also said Russia's claim that it was only attacking military targets was false and civilian sites had also been struck.
Russian forces launched a full-scale invasion in the early hours of Thursday, which is thought to be Moscow’s most aggressive action since the Soviet invasion of Afghanistan in 1979.
By the end of the day, the Ukrainian government said 137 civilians and military personnel had been killed.