An attack on a bus early on Monday morning in northern Syria has killed 13 people, most of them government troops, the country's defense ministry said.
A ministry statement said that 11 government troops and two civilians were killed in what it said was a terrorist attack on a civilian transit bus. It said another three soldiers were wounded.
Syrian state news agency SANA said the attack took place in the Jabal al-Bishri region of the vast province of Raqqa.
The Syrian Observatory for Human Rights said the ambush had been carried out by Islamic State sleeper cells that launch hit-and-run attacks in the country's desert areas. The Islamic State took responsibility for the attack later in the day.
There was no immediate claim of responsibility for the attack.
Background
Syria's 11-year-old conflict has carved the country into various zones of control, with government troops and allied fighters controlling most territory.
A patch of the northwestern territory is held by Turkish-backed rebels and more hardline groups while Kurdish-led forces with US backing hold the northeast.
One of the deadliest bus ambushes was in December 2020, when 28 people were killed in an attack on the main highway in Syria's eastern Deir al-Zor province.