Historic sculptures and cultural objects have been taken from the National Museum of Syria in Damascus, sources confirm.
The burglary was discovered on Monday, when employees apparently found that a doorway had been forced from the inside.
The half-dozen missing pieces were crafted from marble and traced back to the Roman era, one official stated to the Associated Press.
The nation's antiquities authority said it had initiated an inquiry to identify the "circumstances surrounding the loss of a collection of items", and that steps had been enacted to improve safeguarding and monitoring systems.
The chief of domestic security in the capital area, Security Chief Atkeh, was cited by the government press as stating that security forces were probing the robbery, which he said had targeted several "historical artifacts and rare collectibles".
He added that museum protectors at the institution and additional people were being interviewed.
The Damascus Museum, which was established in 1919, contains the primary historical artifacts in Syria.
It contains ancient inscribed tablets tracing back to the Bronze Age from historical site, where evidence of the most ancient linguistic system was discovered; early centuries CE Greco-Roman sculptures from Palmyra, one of the most important ancient sites of the classical era; and a ancient religious building that was built at Dura Europos.
The institution was had to cease operations in the early 2010s, twelve months after the beginning of the internal strife. The majority of the artifacts was transferred and preserved at secure places to ensure their safety.
It reopened partially in recent years and completely reopened in early this year, four weeks after opposition groups removed President Bashar al-Assad.
All six of Syria's Unesco World Heritage sites were affected or partly ruined during the civil war.
The militant faction destroyed multiple ancient buildings and historical sites at the archaeological site, claiming that they were un-Islamic. The cultural organization denounced the destruction as a atrocity.
Countless cultural items were also destroyed or stolen from historical locations and cultural institutions.