A suicide car bomb has exploded on the edge of a Syrian government-held central town, killing two people and wounding four, hours after a ceasefire brought relative calm to parts of the country, the state news agency and opposition activists say.
No one claimed responsibility for the blast on the eastern entrance of the town of al-Salamiyeh, which came hours after the implementation of a ceasefire brokered by the US and Russia began.
The ceasefire went into effect across Syria early on Saturday, marking the biggest international push to reduce violence in the country's devastating conflict.
The truce does not include either the Islamic State group or Jabhat al-Nusra, also known as the al-Nusra Front.
Opposition activists in different parts of Syria said the situation has been "cautiously calm" since the truce went into effect at midnight Friday, reporting sporadic violations.
State TV said the blast occurred near an army checkpoint just outside al-Salamiyeh, where most residents belong to the Ismaili branch of Shi'ite Islam.
The Islamic State group has claimed responsibility for several bombings in Syria that claimed the lives of dozens in recent weeks.
The opposition Britain-based Syrian Observatory for Human Rights (SOHR) said the explosion was the work of IS, adding that the two killed were both soldiers. It added that Syrian warplanes' attacked suspected IS positions in areas outside al-Salamiyeh.
The SOHR said intense fighting is ongoing near the northern town of Khanaser with troops and pro-government militia battling IS.
Battles have been ongoing for five days in the strategic area that is close to the highway that links Aleppo with central and western Syria.
The Syrian government and 97 rebel and militant groups said they will abide by the ceasefire.
In southern Syria, the situation was "calm" on Saturday according to opposition activist Ahmad al-Masalmeh who is based in the southern city of Daraa.
Calm also prevailed in large parts of the central province of Homs, according to Mohammed al-Sibai, who is based in the province.
SOHR reported clashes between the Army of Islam faction and fighters loyal to IS in the Damascus suburb of Dumair.