The Syrian Observatory for Human Rights also said seven people were killed in heavy rebel shelling of government-held areas of Aleppo, which was not one of areas where temporary truces were announced last week. An air strike south of Aleppo meanwhile killed at least three people, it said.
Local ceasefires were announced late last week in the Eastern Ghouta area near Damascus and in northern areas of Latakia province. Washington and Moscow said on Monday they were working hard to extend the truce to Aleppo.
An opposition activist in northern Latakia told Reuters the area had been completely calm for three days.
Jaish al-Islam said in a statement overnight that government forces had taken ground around the town of al-Marj in Eastern Ghouta. The rebel group said the loss had been made easier because of in-fighting with rival rebel groups.
US Secretary of State John Kerry said on Monday he hoped for more clarity in the next day or so on restoring a wider ceasefire, a reference to a Feb. 27 "cessation of hostilities" agreement that has unraveled in recent weeks, particularly in Aleppo.