“Islamic State” (IS) terrorists publicly executed eight Sunni men in a small northern Iraqi village on the weekend for allegedly plotting against the group, an eyewitness from the village told Reuters on Sunday.

The killing began on Friday night when a pair of masked IS gunmen openly murdered a police officer in Al-Jumasah village after the group accused him of spying for the Kurdish and Iraqi military forces, the witness said.

The IS fighters gathered local residents to watch the execution in the village, about 120 km north of Tikrit, the witness told Reuters.

“Islamic State members said that this is the fate of anyone who opposes them,” the witness said. “They presented as evidence CDs and copies of the man’s correspondences with the security forces.”

After the police officer was executed, a small armed group opened fire in revenge on the house of an Islamic State officer. On Saturday morning, the witness said, 10 Islamic State cars drove around Al-Jumasah with two masked informants, who helped the fighters identify 10 people they suspected of attacking their member’s house the previous night.

That evening, three were released and seven others — all but one relatives of the slain policeman — were executed.

News of the executions comes a day after IS released a video showing the execution of British aid worker David Haines in the same grisly manner as the murder of two American journalists in recent weeks.

The video, titled “A Message to Allies of America,” appears to show Haines clad in an orange jump-suit kneeling beside a man who speaks in the same London-accented English as the apparent executioner in two previous videos.

Islamic State had released two previous videos showing the execution of the American journalists James Foley and Steven Sotloff. The group threatened to kill Haines at the end of the Sotloff video.

The group has regularly conducted executions in Iraq and Syria. Last week, an IS-inspired group in the Sinai Peninsula also executed a man it claimed to be an “Israeli spy”.