The US’ key anti-ISIS partners in Syria said on Wednesday that the ISIS detention facilities they guard are coming under attack and that they have been forced to halt anti-ISIS operations, complicating the US military’s efforts to prevent the terror group from reconstituting following the ouster of Syrian President Bashar al-Assad.

NBC News' Richard Engel reports from inside one of Syria's most notorious prisons, Saydnaya military prison nicknamed "the human slaughterhouse." Thousands of people in Syria have rushed to the country's prisons after the fall of the Assad regime searching for any trace of loved ones they feared had disappeared into their unseen depths.

In Syria’s capital Damascus the hope of a country freed from its longtime dictator Bashar al Assad was starting to fade at the city's Saydnaya military prison.