A destroyed building with a wall painted with the black flag commonly used by Islamic State militants is seen in the town of al-Alam March 10, 2015. Reuters

Islamic State group fighters fatally stoned a man and woman accused of adultery in Iraq Tuesday in a public square in the northern city of Mosul, the New York Times reported. The terrorist group, also known as ISIS, has taken to publicly killing people for committing social crimes, including smoking and using cell phones, media reports indicated.

The public stoning involved a couple in their 20s. The woman was wearing a full face veil. “Twelve ISIS militants were standing there who had bags with them filled with stones, and they began throwing the stones at them, and after the third stone the woman was killed,” a witness said. The man was then killed.

“I was moved by the crying of this woman, who started bleeding and then died from the stoning,” one witness told the Times. “I was standing there helpless. The government have left us as captives in the hands of ISIS, who make all kinds of crimes in the city. The more I see their crimes, the more I hate them and realize they have come to carry out a paid agenda to destroy the city and its history and civilization and to defame the image of Islam.”

In October, a man in Syria allegedly stoned his daughter to death after the Islamic State group accused her of adultery. In a video released by the militants, the father dragged his daughter as she begged for her life, the New York Daily News reported.

In September, militants stoned a couple to death in Ar Rutbah in western Anbar province after the pair had been convicted of adultery in an ISIS court, NBC News reported. “They brought the man and the woman, they tied their hands and covered their faces, and started to stone them," a witness said.

Meanwhile, the Syrian Observatory for Human Rights on Tuesday said ISIS had recruited at least 400 children in Syria in the past three months for military training and hardline indoctrination. "They use children because it is easy to brainwash them. They can build these children into what they want, they stop them from going to school and send them to IS schools instead," said Rami Abdulrahman, head of the British group.

ISIS declared a caliphate last year after taking territory in Syria and Iraq. U.S.-led airstrikes have targeted the group.