ISIS militants stoned a couple to death in an Iraqi town as a crowd watched powerless to stop the brutal attack, according to a witness. "It is a terrible scene I wish I did not remember," a civil servant who said he was present told NBC News on Thursday. The pair — who were aged in their 30s — had been convicted of adultery in 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. “They brought the man and the woman, they tied their hands and covered their faces, and started to stone them," the witness added, speaking on the condition of anonymity because he feared for his safety. NBC News could not independently confirm the account.

The executioners chose stones "smaller than a baseball" in order to prolong the couple's death, the witness said. The couple screamed in agony for much of the 15 minutes it took them to die, he added. “What ISIS did is exactly what had been mentioned in the Quran — to punish married people who commit adultery. But look, we are in the 21st century, and those insurgents would like to take us back in time. Who knows, maybe they will issue new laws in future, like it is not allowed to drive a car, and we have to use camels instead." Word of the incident, which occurred on Sept. 15, emerged as a U.S.-led coalition pressed on with airstrikes targeting ISIS sites, mainly in Iraq but also neighboring Syria.

The Sunni militants conquered Ar Rutbah on June 22. “ISIS fighters are supported by some people in my town. I have to admit that the town is more secure than before when it was under the control of Iraqi security forces, because they pursued sectarian goals,” the witness added. ISIS has drawn strength from Iraq’s large and frustrated Sunni minority, which has suffered under Iraq’s Shiite-dominated government and its sometimes brutal security forces.

- F. Brinley Bruton