Ten Christians were beheaded and one other was shot dead by an ISIS-linked group in Nigeria in an act designed to coincide with Christmas.

A video recorded before the execution in the war-torn state of Borno shows a group of 12 men and a blurred-out woman pleading for help from Christian organizations and Nigerian President Muhammadu Buhari.

“I appeal to the federal government to come to our aid,” said hostage Bitrus Zakka Bwala, a lecturer at the College of Education in Nigeria’s Yobe State. “As you can see, behind me are fellow Christians who were arrested at various points and brought to the base of the [Islamic State West Africa Province].”

Nigeria's ISWAP, a break-off group of Boko Haram, released a 56-second video the day after Christmas that shows the 11 Christians being slain. After the first was shot, the other 10 were beheaded.

Boko Haram has wreaked havoc in Nigeria since its inception in 2002, killing 60 during a funeral in one attack this summer. The militant group gained worldwide notoriety in 2014 when it kidnapped more than 300 Chibok schoolgirls.

ISWAP has escalated attacks on Christians in the months following the death of Abu Bakr al Baghdadi during a raid led by U.S. special forces.