Coptic Christians prepared to bury seven worshippers — including six from the same family — on Saturday, a day after Islamic militants ambushed three buses carrying pilgrims to a desert monastery in Egypt, wounding 19 others.

A row of white coffins held the dead, which included a 15-year-old boy and 14-year-old girl, ahead of the funeral service. A priest and members of a Christian congregation prayed and chanted over the caskets.

“I mourn with deep sorrow the martyrs who were killed today by treacherous hands which aim to undermine the solid fabric of the nation, and I wish speedy recovery for the injured,” President Abdel Fatah al-Sissi said in a statement on Friday obtained by the Washington Post.

U.S. State Department spokeswoman Heather Nauert condemned the attack in a statement she posted to Twitter.

The local Islamic State group affiliate, which spearheads militants fighting security forces in the Sinai Peninsula, claimed responsibility for the attack south of Cairo in a statement. It said the attack was revenge for the imprisonment by Egyptian authorities of "our chaste sisters," without elaborating.

The attackers opened fire mid-afternoon on two buses near the Monastery of St. Samuel the Confessor in Minya, 160 miles up the River Nile from Cairo, a church spokesman told Reuters.

A man screams beside a bus carrying Coptic Christians which came under attack outside Cairo, Friday, Nov. 2, 2018. (Egypt’s Coptic Orthodox Church via AP)

Reports say the militants were driving two or three SUV-type vehicles.

“A number of masked men got out of them, took the mobile phones of the passengers and then shot all the men dead,” Bishop Aghathon Tala’at, a Christian community leader, told the Washington Post. “They were wearing military-like uniforms, survivors told me.”

The Interior Ministry said police were pursuing the attackers, who fled the scene.

The Islamic State has repeatedly vowed to go after Egypt's Christians as punishment for their support of el-Sissi. As defense minister, el-Sissi led the military's 2013 ouster of an Islamist president, whose one-year rule proved divisive. It has claimed responsibility for a string of deadly attacks on Christians dating back to December 2016.

In Minya, the scene of Friday's attack, Christians constitute the highest percentage of the population — about 35 percent — of any Egyptian province. It's also in Minya where most acts of violence, like attacks on churches and Christian homes and businesses, take place.

The Associated Press contributed to this report.