The attack occurred on a highway between Day al-Zawr and Palmyra at 13:40 local time on Sunday, Syria’s official news agency SANA reported.
The news agency cited a military source as saying that militants based in al-Tanf area in the province of Homs opened fire at a bus carrying Syrian soldiers in Al Malha-Al Shola area.
Ten soldiers were also wounded in the attack, the source added.
Syria has been gripped by foreign-backed militancy since March 2011. The Syrian government says the Israeli regime and its Western and regional allies are aiding the Takfiri terrorist groups that are wreaking havoc in the country.
The government forces have already managed to undo militant gains across the country and bring back almost all of Syrian soil under government control.
The Sunday assault came about a week after reports said the US had transported Daesh terrorists held in prisons controlled by the US-backed Syrian Democratic Forces (SDF) to its bases in al-Tanf.
The US and its allies purportedly fighting Daesh have been conducting airstrikes and operations inside Syria since September 2014 without any authorization from the Damascus government or a United Nations mandate. Damascus has repeatedly condemned the airstrikes.
The military alliance has repeatedly been accused of targeting and killing civilians. Washington is widely believed to have been supporting Takfiri groups.
Numerous accounts have emerged about airlifts, weapon air-drops and aerial support for Daesh in Syria and Iraq.