The truce took effect 1 a.m. local time (2300GMT) Thursday and allows civilians to immediately leave the area by buses pending no violations of the agreement.
Commanders, who spoke on condition of anonymity due to restrictions on talking to media, said the deal announced was given to frontline opposition fighters.
Opposition sources said civilians with vehicles would begin to leave the area after the truce took hold. In addition, buses will transport civilians and opposition fighters until the morning, once violations did not occur.
Turkish intelligence sources told Anadolu Agency that the deal was reached after talks between Turkey and Russia. They said Turkey is the guarantor for the opposition while Russia is guarantor for Syrian regime forces.
Residents from the besieged area are expected to arrive in Idlib, controlled by opposition forces.
Idlib is located southwest of Aleppo.
Late on Tuesday, the Assad regime and Syrian opposition forces agreed to a Turkish-brokered cease-fire to allow the evacuation of civilians from eastern Aleppo.
Witnesses in Aleppo who previously spoke to Anadolu Agency said regime forces and allied militias breached the deal Wednesday.
Dozens of civilians were injured Wednesday as the regime of President Bashar al-Assad continued to violate the cease-fire, according to a pro-opposition civil defense official in Aleppo.
"The attacks are very intense. More than 40 people have been injured," Najib al-Ansar told Anadolu Agency.
Violence has escalated in the city as Syrian regime forces advanced Monday into opposition-held parts of eastern Aleppo following a five-month siege and persistent aerial bombardment.
The Russian-backed regime had been trying to reestablish control over parts of Aleppo captured four years ago by armed opposition groups.
Syria has been locked in a devastating civil war since early 2011 when the regime cracked down on pro-democracy protests -- which had erupted as part of the Arab Spring uprisings -- with unexpected ferocity.
Since then, hundreds of thousands of people are believed to have been killed by the conflict and millions more displaced.