(CNN) Around 50,000 civilians are still trapped inside Aleppo's rebel-held zone, the UN estimates. Some of them are now going online, posting first-hand accounts of what's happening there.
A ceasefire brokered by Turkey with Russia for eastern Aleppo collapsed less than a day after it was implemented. Turkish officials and activists on the ground accused the Syrian regime and other forces of heavy shelling and bombardment.
Lina Shamy, an activist in eastern Aleppo, tweeted: "Assad & Iranians broke the ceasefire. the genocide still ongoing!"
In a video message, she added: "Civilians are stuck in the city again and no one can leave the city under this agreement."
READ: Syrians post 'goodbye' messages from eastern Aleppo
The ceasefire was supposed to allow both rebels and civilians evacuate. But by late afternoon, it hadn't taken place, and people were still trapped as the fighting raged.
Bilal Abdul Kareem, a Syria-based journalist for On the Ground News, confirmed that the shelling had not stopped.
"After an agreement was reached last night, regime forces are intensely shelling the Aleppo. People must stay engaged," he tweeted.
Kareem, who has worked with CNN in the past, said rebels are ready to surrender and move out of the city.
However, Salah Ashkar, another activist in Aleppo, said "shelling and bombardment are back and all civilians are in total panic and hiding in shelters."
Bana, a 7-year-old girl who is now internationally known for her Twitter account detailing her life in besieged Aleppo, has also been recording the intense bombing taking place.
"I am talking to the world now live from East Aleppo. This is my last moment to either live or die," she tweeted on Tuesday.
Her mother, Fatemah, tweeted from the account on Wednesday.
"Dear world, there's intense bombing right now. Why are you silent? Why? Why? Why? Fear is killing me & my kids."
The Syrian regime entered war-ravaged Aleppo on November 27. In just over two weeks, they've seized control of most of it.
Turkish President Recep Tayyip Erdogan on Wednesday accused the regime of breaking the truce.
"Turkey will not leave the people of Aleppo alone," he said, according to state-run news agency Anadolu.
"I call all parties and international society to respect the ceasefire, to support it. A humanitarian corridor should be open and innocent people should be able to leave with no obstacle and sabotage. People of eastern Aleppo should leave safe and sound."
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