Syrian regime forces violated the cease-fire only half an hour after it came into effect, Qatari news outlet Al Jazeera, local sources and Syrian journalists reported early Friday.
"Regime forces continue bombardments in the south of Idlib and west of Aleppo in violation of the cease-fire deal," Al Jazeera said in a tweet.
Mohamad Rasheed, a Syrian journalist and media expert, also said in a tweet that Assad forces, based in Jourin, a town in the west of Hama, targeted the villages of al-Ghab with heavy artillery.
A local news outlet, Aleppo Media Center also said in a tweet that "Missile shelling by the regime forces was reported in the town of Al-Abzmo in the western countryside of Aleppo."
Turkey and Russia reached the agreement earlier on the same day during a meeting between President Recep Tayyip Erdoğan and his Russian counterpart Vladimir Putin in Moscow.
The meeting came amid growing tension in northern Syria's Idlib province, where the Russia-backed Bashar Assad regime offensive has targeted civilians and Turkish soldiers, raising the prospect of a direct clash between Russian and Turkish forces.
The Syrian regime and its allies, Russia and Iran, have consistently broken the terms of the 2018 cease-fire and a new one that began on Jan. 12, launching frequent attacks inside Idlib.
Especially since April 2018, the attacks on the last opposition stronghold dramatically intensified and caused new waves of refugee flows that move toward the Turkish border, putting the country, which already hosts 3.7 million Syrian refugees, into a difficult position.
As a result, Turkey, which has the second-largest army in the transatlantic NATO alliance, has funneled troops and equipment into the region in recent weeks to stop the Syrian regime advance and avoid the wave of refugees.
However, the killing of more than 34 Turkish soldiers in regime attacks last month acted as a tipping point in regional tension. In response, Ankara launched Operation Spring Shield against regime targets in Idlib.
