File photo of ruined columns at the historical city of Palmyra, in the Syrian desert
File photo of ruined columns at the historical city of Palmyra, in the Syrian desertReuters File

The Islamic State (Isis) militants have reportedly killed more than 400 people in Syria's ancient city of Palmyra.

A Reuters report citing Syrian state television stated that the Isis executed at least 400 people, most of them women and children, after it seized the city. Local residents inside the UNESCO heritage site, famous for its Roman-era ruins, claim that the streets of Palmyra is littered with bodies of the people killed by the Isis.

There are also unconfirmed reports that a Syrian nurse, who some claim also holds American citizenship, was among those executed by the Islamic State militants.

Syrian journalist Leith Abou Fadel on Sunday said on Twitter that the nurse was identified as Hala Malek Wardeh. "Hala Malek Wardeh of Jableh was a nurse at Palmyra National Hospital. She was executed by the criminals of ISIS," he said.

A pro-Syrian Twitter account - Emre Argüello @emre_arguello claimed that the slain Palmyra National Hospital nurse was an American national and was executed by Isis on charges of aiding the Syrian army.

The capture of the modern city of Palmyra located next to the UNESCO World Heritage site, also known as Tadmur in Arabic, has sparked an international alarm. 

UNESCO already has sounded alarm and has said that the destruction of Palmyra by the Isis would be "an enormous loss to humanity".