The United Nations humanitarian office has said that people who are trapped in Mariupol, Ukraine were desperate.
It comes after Ukrainian President Volodymyr Zelensky said that further attempts will be made today to deliver food and medicine to the besieged coastal city.
"There are reports of looting and violent confrontations among civilians over what little basic supplies remain in the city," the Office for the Coordination of Humanitarian Affairs said.
"Medicines for life-threatening illnesses are quickly running out, hospitals are only partially functioning, and the food and water are in short supply."
An adviser to the Ukrainian presidency said earlier that 79 evacuation buses and two trucks with humanitarian cargo had left for Sumy today.
Buses and trucks also left Zaporizhzhia for Mariupol, a video released by the deputy head of the Ukrainian presidential administration on social media showed.
Meanwhile, the International Committee of the Red Cross said that there is no electricity, water and gas supply in Mariupol.
In a post on Twitter, it said that workers in the besieged city reported that there was no way to find medicine there.
"People are getting sick already because of the cold," the ICRC staff member said.
Our colleagues in #Mariupol are taking shelter in our office.
— ICRC (@ICRC) March 12, 2022
This is how one described the situation 👇
In a video address, President Zelensky said a total of 7,144 people were evacuated from Ukrainian cities yesterday.
The figure is far fewer than the numbers who managed to escape in each of the previous two days.
Ukrainian authorities said almost 40,000 left a number of cities through humanitarian corridors on Thursday, on top of the 35,000 who fled on Wednesday.
Mr Zelensky said inhabitants of Chernihiv, Energodar, Hostomel, and Kozarovichi had managed to escape yesterday.
He accused Russia of refusing to allow people out of Mariupol, where authorities have described the situation in Mariupol as critical.
The Ukrainian president also called on the mothers of Russian soldiers to prevent their sons being sent to war in Ukraine.
In his address, released on Telegram, he said: "I want to say this once again to Russian mothers, especially mothers of conscripts. Do not send your children to war in a foreign country.
"Check where your son is. And if you have the slightest suspicion that your son could be sent to war against Ukraine, act immediately" to prevent him being killed or captured, he said.
The president added: "Ukraine never wanted this terrible war. And Ukraine does not want it. But it will defend itself as much as necessary."
On Wednesday, Russia for the first time acknowledged the presence of conscripts in Ukraine and announced that a number of them had been taken prisoner.
Moscow had previously claimed that only professional soldiers had been sent to fight.
The announcement came as posts from mothers without news of their sons sent to Ukraine multiplied on social networks.
Kyiv last week invited mothers of Russian soldiers captured on its territory to come and pick their children up.
The Ukrainian defence ministry published phone numbers and an email through which they could obtain information about them.
Kyiv claims to have taken dozens of prisoners since the start of the Russian invasion.
During the conflict between Moscow and Chechen separatists in the 1990s and 2000s, many young Russian conscripts were sent to the front, and some were taken prisoner.
In a movement that fuelled anti-war protests in Russia at the time, women mobilised to try and bring their sons back alive or bring their bodies back - even going to Chechnya themselves.
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