But the ceasefire appears to have led to a respite in violence in the five-year civil war.
Staffan de Mistura, UN special envoy for Syria, said there has been a "significant drop in violence" in the wake of the ceasefire.
There were still intermittent incidents. An activist from the Aleppo Media Center, an opposition-aligned group that documents the conflict, said there had been an airstrike overnight on Khan Toman in countryside south of Aleppo.
In general though, the situation remained quiet in Aleppo, with no significant violations, the activist said.
The state-run Syrian Arab News Agency said that rebel groups had breached the truce by firing seven mortars Wednesday morning in the countryside near Homs.
In recent days
[Since the start of the ceasefire] images have emerged from Syria showing people taking advantage of the rare calm to celebrate the Islamic holiday of Eid al-Adha
Terror groups excluded from truce
The ceasefire deal, intended to bring humanitarian relief, calls for a halt to the violence between the Syrian regime and rebel forces.
But it does not cover militant groups considered terrorists, such as ISIS and Jabhat Fateh al-Sham
, formerly known as al Nusra Front.