The sources said that the ISIS has deployed its security forces at all city gates and entrances and has launched a serious chase after the fugitives in al-Mayadeen and the nearby villages.

The prisoners were kept in the house of Sheikh Ghanim al-Mohanna in al-Mayadeen which was occupied by the ISIS forces in 2013 and turned into prison.

The ISIS had decreased its guards around the prison to go unnoticed in the Syrian air force reconnaissance flights.

In a relevant development on Monday, the Syrian warplanes carried out several combat flights over ISIS concentration centers and gatherings in eight different regions, leaving scores of the terrorists dead or wounded.

The Syrian fighter jets bombed ISIS positions in al-Baqaliyeh West of Deir Ezzor, near al-Jafreh, in al-Kassarat region, along al-Thardah mountain in Southern Deir Ezzor and areas near the village of Shola Southwest of Deir Ezzor city, the Southern parts of Deir Ezzor Airbase, near Panorama and near the village of al-Mura'yeh East of Deir Ezzor and the Southern banks of the Euphrates River, inflicting large casualties on the terrorists and destroying their military vehicles, mainly those equipped with machineguns. 

Also on Sunday, Syrian military forces shot down two spy drones of the ISIS terrorist group flying over their positions in Deir Ezzor's districts.

The two unmanned aerial vehicles (UAV) were brought down after they were intercepted over government forces' positions in the neighborhoods of al-Sina'ah and al-Jabaliyeh.

The ISIS drones were equipped with imaging devices, FNA reported.

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