Reports of scattered violence between militants and some rebel groups emerged in Syria on Saturday after a cessation of hostilities went into effect at midnight.
Terrorist groups involved in the clashes, including ISIS and al Qaeda-linked al-Nusra Front, are not part of the truce agreement.
London-based Syria Observatory for Human Rights reported the incidents of violence, but said things are quieter in general.
It reported clashes between regime forces and rebels in Latakia, and other incidents of violence between government forces and ISIS fighters in Aleppo.
In Latakia, 12 rebel fighters were killed in clashes with government forces, according to the observatory.
ISIS, rebels clash
ISIS fighters also clashed with other rebel groups in Aleppo and Homs, the observatory said.
Nevertheless, initial indications showed violence was significantly reduced — a relief to Syrians living in the rubble of bombed-out cities.
U.N. special envoy Staffan De Mistura said immediate reports indicated “suddenly both Daraa and Damascus had calmed down.”
An unusual quiet has descended on major cities in Syria, said Rami Abdulrahman, director of the Syrian Observatory for Human Right. He added there were brief exceptions, including some unexplained explosions reported in the north.
Nobody expects peace to settle over the nation overnight, De Mistura said.
If there are violations, he said, “the important point that we need to see is that if those incidents will be quickly brought under control and contained.”
‘Our best chance’
Another Syria task force meeting will take place Saturday afternoon in Geneva to assess whether the truce is being respected, he said.
The cessation of hostilities is the most hopeful sign in years in the nation, where the conflict has killed at least 250,000 people.
Earlier Friday, the Security Council voted unanimously in favor of a resolution backing the halt in fighting and asking for all parties to abide by the terms of the cessation.
A main Syrian opposition group said it will respect the two-week truce that starts with the cessation of hostilities. But it warned the government and Russia not to target it under the pretense of attacking terrorist groups such as ISIS.
The rebel High Negotiations Committee said 97 factions have agreed to abide by the deal. But it warned Syria and one of its major foreign supporters, Russia, not to attack them under the pretense of targeting ISIS and al-Nusra Front.