ISIS militants stoned a couple to death in a town in Iraq as a crowd watched, unable to do anything.

According to a witness speaking to NBC News said,

NBC News reports that the couple who are said to be in their 30s were convicted of adultery by an ISIS court. They were then led out in front of a crowd of some 200 residents in Ar Rutbah in western Anbar province, who stood by as eight fighters carried out the execution.

the witness added, speaking on the condition of anonymity because he feared for his safety.

, the witness said.

The couple screamed in agony for much of the 15 minutes it took them to die, he added.

the witness added.