Aleppan activists: Here are our last messages before dying

Syria, which has been witnessing war for more than 5 years, has witnessed the most bloody day on Monday, since the beginning of the war, as the regime forces massacred civilians, including women and children, while they burned a large number of people alive, after the Assad regime seized East Aleppo substantially.

The Aleppan activist said that the world didn't hear the screams of the civilians through Twitter.

"They are slaughtering humanity in Aleppo. Thousands of civilians are expecting to be rescued; however, the rest of the world doesn't hear their voices," activists wrote.

"My father is wounded. A lot of people are being killed one by one silently. I am surprised that I am still alive," a 7-year-old boy wrote on Twitter with his mother's help.

"Please tell our story to the whole world, so that my son can be proud of me," a wounded father wrote before gasping his life out.

An activist called "Shero Alo" wrote "Goodbye world" in his last tweet before being killed.

On late Monday, the Assad regime seized East Aleppo substantially. Regime forces massacred civilians, including women and children, while they burned a large number of people alive.

Thousands of civilians may be put in harm's way as Syrian government forces overrun the last opposition-held neighborhoods of east Aleppo, human rights groups and residents said on Monday.

The Syrian government has taken control of at least 97 percent of east Aleppo after intense bombardments, according to the Syrian Observatory for Human Rights, a U.K.-based monitoring group.

Seizing the remaining territories would grant President Bashar al-Assad a strategic victory, returning all urban centers in the country to his control. Airstrikes continue to pound the collapsing opposition-held areas, where tens of thousands of civilians remain trapped, the observatory said.

The International Committee of the Red Cross asked all sides to spare the lives of civilians caught in the crossfire.

Meanwhile, Turkish President Recep Tayyip Erdoğan and his Russian counterpart Vladimir Putin have spoken three times over the phone on the northern Syrian province of Aleppo, which has been under intense attacks from the Russia and Iran-backed Bashar al-Assad regime.

The talks aim to make a significant decision, which may initiate the formation of a corridor to evacuate the moderate opposition and civilians.

Russia and the Assad regime are known to bomb Aleppo, the Syrian province located 50 kilometers from Turkey, as a part of terrorist organizations' and Assad's target to control northern Syria by taking the land from the moderate opposition.

The civil war in Syria has killed more than 250,000 people, according to the United Nations. The Syrian Center for Policy Research has established that the total death toll from conflict stands at more than 470,000.