A leading rights group on Monday called on Egyptian authorities to quash blasphemy sentences handed down to four teens and their teacher for a video they made mocking ISIS.

An Egyptian court convicted the four Christian teenagers for contempt of Islam on February 25 after they appeared in the video appearing to make fun of Muslim prayers, according to The Associated Press. Three were sentenced to between three and five years in prison while a fourth was referred to a juvenile detention facility, the news agency added.

Human Rights Watch said Monday that "these children shouldn’t face prison for expressing themselves, even with an immature joke" and urged Egypt to protect free speech "instead of giving in to retrograde views" about blasphemy.

"Mocking ISIS, or any religious group, with a childish joke is not a crime,” Nadim Houry, deputy Middle East director at Human Rights Watch, said in a statement.

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The teens were not present at their sentencing and have yet to turn themselves in or be apprehended, the group said. It named the four as Mueller Edward, 17; Bassem Hanna, 16; Alber Ashraf, 16; and Clinton Yousef, 17. Their teacher, Gad Yousef Younan, was sentenced to three years in a separate trial.

Two relatives of the teens told the AP that Younan filmed the video shortly after an ISIS affiliate released images of 21 abducted Christians being beheaded in Libya. The teens are members of Egypt's ancient Coptic Christian minority from Minyam, a region around 160 miles south of Cairo where 20 of those killed in the ISIS beheading video are from.

According to the AP, the 30-second video showed the four pretending to pray, with one kneeling on the floor while reciting Quranic verses and two others standing behind him and laughing. One waved his hand under a second's neck in a sign of beheading.

The video prompted calls by angry Muslims to evict the students and the teacher from their village of Bani Mazar, AP reported. Mobs attacked the students' houses in the village and security forces arrested the students while the teacher and his family were ordered to leave the village after a meeting of the village elders, the news service added.

The two relatives told Human Rights Watch that soon after the video came to light authorities detained the four in in the same cells as adults and criminal suspects — a violation of Egyptian law.

Related: U.S. Condemns ISIS' 'Heinous' Beheading of 21 Christians

The teens "didn’t talk much about what happened inside," Edward’s father told Human Rights Watch. "My son got 98 percent in the high school exams, even though they were taking the exams inside the police station."

"He’s loved by his Muslim colleagues. They were the first ones to warn us that something bad might happen," added the father, who Human Rights Watch did not name. "They were psychologically troubled by the killings of Coptic Christians in Libya and went for entertainment. They didn’t deliberately intend any offense…. How can you try someone for mocking ISIS?"

Egypt's Coptic Christians, who make up around 10 percent of the country's population, have complained of discrimination at the hands of the Muslim majority.