Valuable statues and additional items have been taken from the National Museum of Syria in the capital, authorities report.
The theft was discovered on Monday, when museum workers allegedly found that one of the museum's doors had been damaged from the inside.
The half-dozen taken statues were crafted from marble and originated to the Roman period, one official stated to the news agency.
Syria's Directorate-General for Antiquities and Museums said it had opened an investigation to establish the "events surrounding the disappearance of a collection of artifacts", and that steps had been implemented to strengthen safeguarding and surveillance.
The head of domestic security in the capital area, General Osama Atkeh, was quoted by the official media as stating that law enforcement were investigating the robbery, which he said had targeted several "ancient sculptures and unique items".
He added that guards at the museum and additional people were being interrogated.
The National Museum, which was established in the early twentieth century, contains the most important historical artifacts in Syria.
It contains historical records originating to the ancient era from an ancient city, where proof of the earliest complete alphabet was uncovered; Greco-Roman period Greco-Roman sculptures from Palmyra, one of the most important cultural centres of the ancient world; and a 3rd Century AD synagogue that was established at an ancient location.
The museum was had to cease operations in the early 2010s, twelve months after the beginning of the internal strife. Most of the collection was evacuated and stored at secure places to ensure their safety.
It began limited operations in 2018 and completely reopened in early this year, a month after insurgents deposed Syria's former leader.
Every one of nationally recognized sites were harmed or partially destroyed during the civil war.
The IS organization blew up multiple temples and historical sites at the archaeological site, stating that they were idolatrous. The cultural organization denounced the demolition as a war crime.
Numerous historical objects were also destroyed or taken from dig sites and collections.