Under pressure from Russia and the United States, the Syrian army agreed on Wednesday to respect a two-day truce in the war-ravaged city of Aleppo.
The Syrian climb-down came after Washington said the United States and Russia had agreed to push the warring parties to extend their shaky ceasefire.
"A truce will be in place in Aleppo for 48 hours from 1:00 am on Thursday (2200 GMT Wednesday)," Syrian army command said, according to state media.
The Russian defense ministry said Russian ceasefire monitors had agreed with their American counterparts to oversee this truce until midnight on May 6.
But for his part, Secretary of State John Kerry said a new Aleppo truce had already begun at 2101 GMT and that violence had already fallen off.
On the ground, AFP correspondents said fierce fighting continued in both Aleppo and an area west of Damascus that was already under the ceasefire regime.
"We've seen an overall decrease in violence in those areas even though there are some reports of continued fighting in some locations," Kerry said.
Kerry added that U.S. officials in Geneva are coordinating with their Russian colleagues on "enhanced monitoring efforts for this renewed cessation."
And he stressed that for Washington, the "cessation of hostilities" must spread nationwide and underpin a return by both sides to peace talks in Geneva.
Russia and the United States were joint sponsors of a previous February 27 ceasefire agreement that had begun to fall apart, especially around Aleppo.
The city is divided between Bashar Al-Assad's government forces, Western-backed opposition forces and Al-Nusra Front rebels not party to the ceasefire.
Last week, Russia agreed to a ceasefire in Latakia and a suburb of Damascus but said Assad should be allowed to fight Al-Nusra "terrorists" in Aleppo.
Intense fighting continued in the city, and hospitals in both rebel and government-held areas were hit, amid some of the worst civilian casualties of the war.
On Sunday, Kerry flew to Geneva for talks with UN peace envoy Staffan de Mistura, who in turn went to Moscow for talks with Russian Foreign Minister Sergei Lavrov.
By Wednesday, Kerry felt confident enough in Russia's "buy-in" to the process that the State Department was able to announce what it hopes will be a new truce.
Nevertheless, in Aleppo, new explosions could be heard.
Rami Abdel Rahman, head of the London-based Syrian Observatory for Human Rights, said the fighting was "the most violent in Aleppo in over a year".
According to the Syrian state news agency SANA, in recent days rebels have fired a barrage of rockets into regime-held neighborhoods in western Aleppo.
Three more civilians were killed in the attacks early on Wednesday, it said.
Regime warplanes struck the advancing rebels, giving opposition-held areas of eastern Aleppo a respite from the bombing, an AFP correspondent in the city said.
Suspected regime strikes also pummeled the rebel stronghold of Eastern Ghouta near Damascus, after a temporary freeze in the area expired overnight.
Kerry confirmed these strikes, but said the joint U.S.-Russian ceasefire monitoring center which is being set up in Geneva would redouble its efforts.
AFP contributed to this report.