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On day eight of the invasion, residents of Mariupol have been describing a relentless barrage of shelling as Russian forces try to surround and capture the port city.
IT developer Maxim told the BBC's Joel Gunter he and his grandparents were "terrified" as they sheltered in a sixth-floor apartment which the elderly couple are unable to leave.
The city's deputy mayor Serhiy Orlov said the whole city was now without power, water or sanitation.
"We are getting completely cut off - destroyed by artillery. Only the natural gas supply is left," he said.
Mariupol is at a key strategic location. Its fall would allow Russian troops advancing east from Crimea to link up with pro-Russian separatists from Donbas.
Earlier we reported that Russian forces had taken control of another important city, Kherson.
It is the first major population centre to be captured by Russia in more than a week of fighting.
You can see more maps showing what we know of the day's developments here: Tracking Russia's invasion in maps
Bombed-out city
Scenes of destruction are becoming increasingly familiar in this war.
Especially harrowing footage has emerged from the town of Borodyanka, north-west of Kyiv, where drones showed the extent of the damage in residential districts.
Destroyed Russian military vehicles also feature, and locals claim they have repelled a Russian assault on the town.
Russia to continue its campaign - Putin
Despite the ongoing fighting and bombardments, efforts at diplomacy have been limping on.
Russian and Ukrainian negotiators met at an undisclosed location on Thursday. The two sides are reported to have agreed to the possibility of temporary local ceasefires to organise humanitarian corridors.
Meanwhile French President Emmanuel Macron attempted to persuade his Russian counterpart Vladimir Putin that the invasion was a serious mistake and that his view of the situation did not correspond to reality.
Unsurprisingly, there was little common ground between the two leaders during their 90-minute phone call. Mr Putin said Russia would continue its campaign until it fulfilled its goals, including the "demilitarisation" of Ukraine.
Later at a meeting with his Security Council, Mr Putin said he would never give up on his conviction that Russians and Ukrainians were one people.
'We are warriors'
Outside the Ukrainian capital Kyiv, the BBC's Orla Guerin has been speaking to Ukrainian volunteers preparing to defend the city.
Deep in a forest, they are digging trenches to block the path of a possible Russian advance within days.
The scene is somehow reminiscent of World War Two, our correspondent says. There's no heavy machinery, she adds, just a shovel in every hand - a rush job to block the path of Russian forces.
"I am preparing to fight for my motherland with my friends," said 36-year-old lawyer Denys. "Now we are warriors, and we will defend the country from the aggressor, the occupier. We will fight to the last drop of our blood."
Russian troops have so far been unable to break into Kyiv, although a huge military convoy has been almost stationary just to the north of the city for several days.
Estonian ship goes down
Returning to the south of Ukraine, an Estonian-owned cargo ship has sunk following an explosion near the Ukrainian Black Sea port of Odesa.
Ukrainian reports said the ship was being used as a shield by Russian naval forces against Ukrainian weaponry.
All six crew members were rescued.
Baltic state Estonia is a member of Nato and has a border with Russia.
Oligarchs sanctioned
The UK has extended its sanctions regime against Russia to two more oligarchs close to the Kremlin.
Alisher Usmanov's company USM has had sponsorship ties with English Premier League football teams Arsenal and Everton, while Igor Shuvalov was at one time Mr Putin's deputy prime minister.
Their assets will be frozen and they will be banned from the UK.
Another tycoon, oil company Rosneft's CEO Igor Sechin, had his yacht confiscated by French customs officers.