Valuable artifacts and cultural objects have been removed from the National Museum of Syria in Damascus, authorities report.
The robbery was found on Monday, when museum workers apparently found that one of the museum's doors had been forced from the interior.
The multiple missing pieces were made of marble and traced back to the ancient Roman times, a source stated to the Associated Press.
Cultural heritage officials said it had opened an investigation to identify the "events surrounding the disappearance of a collection of artifacts", and that measures had been taken to improve security and observation methods.
The director of domestic security in the Damascus region, Security Chief Atkeh, was quoted by the government press as saying that authorities were probing the robbery, which he said had focused on several "archaeological statues and rare collectibles".
He noted that guards at the institution and other persons were being questioned.
The Damascus Museum, which was established in 1919, houses the primary historical artifacts in Syria.
It features clay cuneiform tablets tracing back to the ancient era from an ancient city, where indications of the oldest known writing system was found; Greco-Roman period ancient art from Palmyra, a significant cultural centres of the classical era; and a 3rd Century AD Jewish temple that was constructed at another archaeological site.
The facility was compelled to shut in 2012, twelve months after the beginning of the internal strife. Most of the collection was evacuated and preserved at secret locations to ensure their safety.
It partially resumed in 2018 and completely reopened in early this year, a month after insurgents deposed the Assad regime.
All six of nationally recognized sites were harmed or partly ruined during the civil war.
The IS organization blew up several ancient buildings and other structures at the ancient city, claiming that they were against their beliefs. Unesco denounced the destruction as a atrocity.
Countless historical objects were also lost or looted from historical locations and cultural institutions.