The fierce battle for the Ukrainian city of Debaltseve is continuing Thursday, despite calls from the Organization for Security and Co-operation in Europe to hold a three-day ceasefire to allow thousands of trapped civilians to evacuate.

The city has been under siege by pro-Russian rebels since Jan. 17, and has turned into the newest focal point of fighting in the war, as well as another symbolic theatre of battle for the Ukrainian army since it lost Donetsk airport to heavily armed rebels last month. Gaining control of Debaltseve, a major transport hub just 75 kilometers (45 miles) from Donetsk, would give the rebels access to important routes within the self-proclaimed republics of Luhansk and Donetsk.  

“The situation in Debaltseve is catastrophic,” said Joanne Mariner, a senior crisis response adviser at Amnesty International, to the Kyiv Post. “I have spoken to many elderly people who are confined to their basements, living in extremely dire, overcrowded conditions, in absolute fear. Many told me how they felt completely lost, not knowing what to do. Shelling is constant. These people are at the mercy of forces they have absolutely no control over.” 

Ten thousand people, or more than half the city’s population, remained trapped inside the besieged town under shelling by Russian-backed militants, according to Viktor Nechytailo, a Ukrainian government official in the Donetsk region. 

"Unfortunately, not everyone who is in basements and bomb shelters wants to leave the town,” said Nechytailo. “We provide these people with first aid, we deliver water and medicines. We brought them a generator from the City Council so that they could have light and could charge their phones. However, there are no mobile communications yet.”

According to media reports and pictures coming out of the region, residents are being forced to cook from makeshift stoves and use water from outside, as apartments have been cut off from power and water. According to Amnesty International, elderly people are most at risk.

Meanwhile, nearly 200 kilometers (120 miles) from Debaltseve in the port city of Mariupol, Ukrainian forces have successfully repelled pro-Russian separatists, whose shelling of the area had killed 30 people a week ago. Ukrainian forces have been keen to defend Mariupol, as losing the city to the rebels would go a long way to creating a land bridge between the pro-Russia Donetsk region and Crimea to the south, which Russia annexed last year.

The UN has reported that over 5,300 people have been killed in the conflict so far.