Video purports to show ISIS beheading Christians

CAIRO - A video released by militants in Libya claiming loyalty to the Islamic State of Iraq and Syria (ISIS) purports to show the mass beheading of Coptic Christian hostages.

The video, released late Sunday night, shows several men in orange jumpsuits being led along a beach, each accompanied by a masked militant. The men are made to kneel and one militant addresses the camera in English before the men are simultaneously beheaded.

The makers of the video identify themselves as the Tripoli Province of ISIS - the Islamic militant group that controls about a third of Syria and Iraq. Militants in Libya claiming affiliation with ISIS had been holding 21 Egyptian Coptic Christians hostage for weeks.

The Associated Press could not immediately independently verify the video.

CBS News' Alex Ortiz reports that a state news agency said Egyptian President Abdel Fattah el-Sissi has summoned an urgent meeting of his national defense council and declared seven days of mourning following the release of the video.

Libya has descended into chaos more than 3 years after a U.S.-backed uprising toppled the country's longtime dictator Muammar Qaddafi, as various tribes, militias, political parties and religious groups battle for power.

The problem has been particularly acute in the country's east, where several Islamist groups are reported to have been battling for control.

French forces largely expelled al Qaeda-linked insurgents from northern Mali in 2013 and some fled to Libya.

Late last year, Gen. David Rodriguez, the head of the U.S. Africa command,warned that ISIS had begun setting up training camps in the country's east.

Secretary of State John Kerry called Egyptian Foreign Minister Sameh Shoukry, according to a senior state department official to offer his condolences. He strongly condemned the killings and the two agreed to remain in touch as Egypt decides on a response.