Updated

Egypt's military fought back against the attackers who stormed a bus full of Coptic Christians and killed 28 people on their way to a monastery to pray, President Abdel-Fattah el-Sissi said Friday.

The Egyptian military struck bases where the attackers had trained, the president said without elaborating. No group immediately claimed responsibility for the attack, but Egypt’s Coptic Christians have become the preferred target of the Islamic State in the region.

"I direct my appeal to President Trump: I trust you, your word and your ability to make fighting global terror your primary task," el-Sissi added in a televised speech. Trump condemned the attack, blaming what he called "evil organizations of terror" and "thuggish ideology."

As many as 10 attackers in 3 SUVs stormed the bus dressed in military uniforms and wearing masks, before demanding that the passengers recite the Muslim profession of faith, according to witnesses. Then, the gunmen opened fire. Some 22 people were wounded.

Only three children survived the attack, the Copts United news portal reported. The victims were on their way to visit a monastery to pray.

Survivors claimed the killers left behind flyers about the holy Muslim month of Ramadan, which begins Friday evening.

Video circulating on social media after the attack showed the bodies of about 10 men scattered in the sand on the side of the road with pools of blood around them. Children hysterically screaming could be heard in the background. Local media also reported that the attackers were recording video themselves.

Arab TV stations also showed images of the badly damaged bus along the roadside, many of its windows shattered and with numerous bullet holes. Footage of the bus's interior showed blood stains on the seats and shattered glass.

Egypt's Copts, the Middle East's largest Christian community, repeatedly have cried out for help from discrimination, as well as outright attacks, at the hands of the country's majority Muslim population. Coptic Christians account for about 10 percent of Egypt's 93 million people.

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Among the wave of recent attacks on Egypt's Christians: twin suicide bombings on Palm Sunday in April and another attack in December on a Cairo church, caught on video. ISIS in Egypt claimed responsibility for them and vowed more attacks.

"The government must be more intentional about protecting vulnerable minorities and punishing the attackers. Continual support for displaced families is vital, whether it is food, housing, or medical care. Our thoughts and prayers are with the victims and their families during this difficult time," human rights group International Christian Concern's Regional Manager William Stark said.

Many of Egypt's Christians rallied behind the general-turned-president, Abdel Fattah el-Sisi, in 2013 when he ousted his Islamist predecessor Mohamed Morsi, who hails from the Muslim Brotherhood group. Attacks on Christian homes, businesses and churches have surged in the ensuing years, especially in the country's south.

In February, members of an ISIS affiliate released a video saying that Egyptian Christians were their "favorite prey." The video showed images of a suicide bomber who killed nearly 30 people inside a packed Cairo church in December.

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"God gave orders to kill every infidel," one of the militants carrying an AK-47 assault rifle said in the 20-minute video.

The bus was traveling on the road to the St. Samuel the Confessor Monastery in the Minya Governorate, about 140 miles south of Cairo, the health ministry said.

On Wednesday, the U.S. Embassy in Cairo issued a security message, stating that it was aware of a potential threat posted on a website by the Hassm Group, a known terrorist organization, suggesting some kind of unspecified action that evening.

Pope Francis visited Egypt late last month, in part to show his support for Christians in this Muslim majority Arab nation who have been increasingly targeted by Islamic militants. During the trip, Francis paid tribute to the victims of the December bombing at Cairo's St. Peter's church, located in close proximity to Cairo's St. Mark's cathedral, the seat of the Coptic Orthodox Church.

Fox News' Perry Chiaramonte and The Associated Press contributed to this report.