ADDIS ABABA, Ethiopia -- Ethiopia's government on Monday declared three days of mourning after confirming that several Ethiopians held captive in Libya were killed by the Islamic State of Iraq and Syria (ISIS), which over the weekend released a video purporting to show the killings.
The days of mourning will start Tuesday, when lawmakers will meet to discuss the killings and consider the country's possible response, the governmment said in a statement.
The national flag will also fly at half-staff during the mourning days.
A 29-minute video, released on Sunday via social media accounts and websites used by the extremists, shows many Ethiopian Christians held captive in Libya being shot or beheaded by militants.
Redwan Hussein, an Ethiopian government spokesman, said on Sunday that he believed the victims were Ethiopian migrants trying to reach Europe.
Abune Mathias, the head of Ethiopia's Orthodox Tewahedo Church, condemned the killings, urging "all Ethiopians to show the perpetrators that their actions amounts to nothing other than a pure brutality."
Ethiopia long has drawn the anger of Islamic extremists over its military's attacks on neighboring Somalia, whose population is almost entirely Muslim. While a militant in the video at one point said "Muslim blood that was shed under the hands of your religion is not cheap," it did not specifically mention the Ethiopian government's actions.
The ISIS video showing the killing of the Ethiopians starts with what it called a history of Christian-Muslim relations, followed by scenes of militants destroying churches, graves and icons. A masked fighter brandishing a pistol delivers a long statement, saying Christians must convert to Islam or pay a special tax prescribed by the Quran.
In the recent video, a man identified as a Christian said he's safe and happy living under ISIS.
But CBS News' Alex Ortiz reports ISIS has a well-documented history of targeting religious minorities in Syria and Iraq, massacring civilians, and desecrating churches.
ISIS has been able to gain a foothold amid the chaos in Libya as it 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.