Islamic State militants in Iraq publicly executed 50 members of a Sunni tribe on Sunday, including women and children, officials told the Associated Press.
Members of the Sunni Al Bu Nimr tribe were lined up and fatally shot one by one by the extremists in the Anbar province village of Ras al-Maa, Sheikh Naim al-Gaoud, a senior tribesman, told the AP.
An unidentified Anbar government official also confirmed the killings, the latest in a series of mass murders committed by IS, also known as ISIS or ISIL, as it continues to seize large swaths of territory in the province as well as other parts of Iraq and Syria.
Another 50 tribe members were slain Friday and 40 more were killed on Thursday, several unnamed officials told the news agency.
The brutal killings show the "reality of what we're dealing with" in the crisis, U.S. Defense Secretary Chuck Hagel said according to the BBC.
Local Sunnis had previously supported IS when it took over other cities in the province in its bid to establish a caliphate. They also protested the Shiite-controlled Iraqi government over what they felt was unfair treatment.
But the jihadists - who have a significant Sunni membership - now seem to view the Al Bu Nimr tribe as a threat, according to the AP.
The Sunni government in Iraq has tried to convince local Sunnis to fight on its side against the militants, seeing the tribe members as invaluable because they have access to areas the U.S.-led air strikes cannot reach.
At least 5,000 tribesman in Anbar have taken up arms alongside Iraqi government forces to fight the Islamic State. But the majority of the tribes, with tens of thousands of members, are holding out for guarantees of some degree of self-rule as well as a say in national decisions, the BBC reported.