The fight for control over the Syrian city of Aleppo continued to roar on the ground and in the skies on Wednesday into Thursday as thousands of civilians still trapped inside begged to be let out.

Among them, desperate activists are turning to instant messaging platforms like WhatsApp to reach international journalists in an urgent call for help.

"'Til this moment, the bombing hasn’t stopped on the besieged districts and nothing has changed on the ground,” Lina Shamy, a Syrian activist, told NBC News through a WhatsApp voice message.

“People here can’t trust anymore if an international agreement came. They can’t trust that they will get out from the besieged city,” Shamy, a 26-year-old activist said from her neighborhood of al-Zabdiya in Aleppo.

A plan to evacuate thousands of people — in a deal between Syrian regime and rebel forces — was delayed Wednesday but was reportedly set to resume Thursday.

"Within the coming hours its implementation will begin," said Abdul Salam Abdul Razak, a military spokesman for the Nour al-Din al Zinki rebel group, according to Reuters.

A man walks next to a destroyed building one day after a ceasefire was announced, at al-Mashhad neighborhood in the rebel-held part of Aleppo, Syria, Dec. 14. STRINGER / EPA

Some Syrian activists say instant messaging remains one of the few means of communicating the stories of suffering inside Aleppo to the outside world, so they are creating WhatsApp groups and adding journalists.

NBC News has been able to independently verify that these activists were in rebel held areas of the Syrian city.

Mohamad Shbeeb, 22, is another Syrian sharing his dispatches through the service.

“It’s really a disaster here, a disaster in all the meaning of the word,” Shbeeb told NBC News via instant message.

"People are too frightened” and they “don’t know what will happen," Shbeeb added.

"We hope that we can protect and keep the lives of the people who are living here. It’s really a disappointment for us to leave our city and to leave the city that we belong to. But to keep the people’s lives is more important than our disappointment,” Shbeeb shared from the Syrian neighborhood of al-Mashad in Aleppo.

A member of the Syrian pro-government forces looks at the damage at a makeshift hospital which was used by rebel fighters in Aleppo's al-Sakhur neighborhood, on Dec. 6, a few days after the area was retaken by the government troops. GEORGE OURFALIAN / AFP - Getty Images

Syria Charity, a French NGO that provides humanitarian and medical aid inside Syria, has also turned to WhatsApp to keep in touch with their aid workers inside Aleppo.

“Right now I’m at the intensive care. I can’t talk every second, but I will update you as soon as I can if I have time,” said a Syrian technician in the group.

“Thank you, I wish you can deliver our voices and our sufferings. I don’t want promises without fulfillment,” he said.