The Islamic State (IS) released a video Sunday that shows the murder of 21 Egyptian Coptic Christians who were kidnapped earlier this year in Libya.

The horrific footage, posted on an IS-affiliated Twitter feed, shows the simultaneous beheading of all 21 prisoners. The victims are shown on a beach in handcuffs and wearing orange jumpsuits. Their captors are dressed all in black with masks covering their faces.

The video, titled "A Message Signed With Blood to the Nation of the Cross," claims to target the "hostile Egyptian church" to avenge "Muslim women persecuted by Coptic crusaders in Egypt." The video was allegedly shot in Libya on "the coast of Wilayat Tarabulus by the Mediterranean Sea."

In the footage, a masked militant addresses the camera, claiming that the when the blood of the Christians enters the sea it will be mixed with the blood of Osama Bin Laden. At the end, the camera pans out to show blood in the water. The militant finishes with a claim that the group will "conquer Rome."

At the end of this Islamic State video on the Libyan seashore in Tripoli, leader turns to Italy and points to Rome — Daniele Raineri (@DanieleRaineri)February 15, 2015

The video surfaced a day after Libya's government confirmed that the 21 Coptic Christians held captive had been murdered, and a few days after IS claimed the execution of the hostages on its English-language publication Al-Dabiq.

The victims were migrant workers from central Egypt. Many were kidnapped on January 4 from their homes in Libya, according to the Telegraph.

"They knew who they wanted, and they asked for them by name," one villager who narrowly escaped the kidnapping told the Telegraph. "They had a list with all our names on it."

Egypt offered to evacuate thousands of its citizens from Libya after reports emerged of the kidnapping.