Military sources revealed that one U.S. soldier was killed in an operation that freed more than 70 ISIS hostages in Iraq. The Kurdish hostages were freed from an ISIS prison in norhtern Iraq near Tikrit where they "were chained to walls," one source said, according to FOX News.

"A mass atrocity was averted," another source said. Special Forces decided to move in once it became clear that ISIS members in the facility were planning to murder the hostages.

Kurdish Special Operations forces, known as Peshmerga, were in the lead during the operation, where forces came down from helicopters after the area was hit with airstrikes, a senior U.S. defense official said, reported DEBKAfile. One part of the force attacked the prison, while the other part secured the roads leading to the facility to prevent the militants inside from receiving reinforcements.

This marks the first U.S. combat fatality on the ground in the fight against ISIS in Iraq and Syria, CNN said, according to Reuters.

On ISIS's part, the jihadist group lost 10 members during the overnight raid.