Residents of Mariupol on Ukraine's southeastern coast are trapped inside the city without electricity and water, its mayor said on Thursday.
Vadym Boychenko said Russian forces have blocked utilities and destroyed routes out of the city.
"They are blocking the supply and repair of electricity, water and heat," Boychenko posted on his Telegram account, according to CNN.
"They have also damaged the railways. They have destroyed bridges and smashed trains so that we can't evacuate women, children and the elderly out of Mariupol."
Hundreds of Mariupol civilians were killed by "relentless" shelling, he said on Wednesday.
They included a teenage boy who was playing football near a school, Associated Press reported.
Senior International Correspondent John Irvine and his team film the moment Russian tanks turn their turrets on the last convoy out of Mariupol
Graphic images from inside a hospital in the city show residents badly injured by shelling as Russian forces attempt to cut the country off from its coastline.
"We are being destroyed as a nation," Boychenko continued. "This is the genocide of the Ukrainian people. These hypocrites came to ‘save’ Russian-speaking citizens of Mariupol and the region, but they arranged the extermination of Ukrainians - Mariupol residents of Russian, Ukrainian, Greek and other origins."
Mariupol residents tell ITV News' John Irvine why they intend to stay despite Russia's advancement
A spokesman for pro-Russian separatists in the Donetsk region told Russian state media on Thursday that humanitarian routes out of the city had been stopped, Interfax news agency reported.
Located on the Sea of Azov, with a population of around a half a million, Mariupol is the second largest city in Ukraine's Donetsk Oblast region and a strategic target for Russian forces.
It's the leading trading port in the region, handling millions of tonnes of cargo every year.
Traditionally a major port for exporting coal and steel, Mariupol is also a key shipping route for wheat, barley and corn, with plans in place for a new grain terminal to push out one million tonnes of grain a year.
Its location would help Russia establish a land corridor between the Crimean Peninsula and the Russian mainland.
Britain’s Defense Ministry said on Wednesday that Mariupol, along with Kharkiv and Kherson, had been encircled by Russian forces.
Mariupol refused to surrender on Thursday, following what deputy mayor Sergei Orlov described as 26 hours of continued shelling, CNN reported.
"The Ukrainian military is not going to surrender the city and will strike at the occupying forces," a Ukrainian National Guard spokesperson told CNN. "The military will also continue to destroy enemy sabotage groups on the outskirts of Mariupol."
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