Gunmen opened fire on a bus in Egypt carrying Coptic Christians to a monastery on Friday, killing at least 28 people and wounding 22, officials said.
No one immediately claimed responsibility for the attack - but it had all the hallmarks of Egypt's Islamic State affiliate.
Egyptian authorities have been fighting ISIS-linked militants, who have waged an insurgency that's mostly focused in the volatile north of the Sinai Peninsula.
The country's Coptic Christians - who are the Middle East's largest Christian community - have emerged as a top target for ISIS.
History of issues
Egypt's Copts, who make up around 10 percent of the country's 92 million population, have repeatedly complained of suffering discrimination and outright attacks at hands of its majority Muslim population. Over the past decades, they have also become targets of Islamic extremists.
Coptic Christians rallied behind the country's general-turned-president, Abdel-Fattah el-Sissi, in 2013 when he ousted Islamist predecessor Mohammed Morsi, who hails from the Muslim Brotherhood group.
Attacks on Christian homes, businesses and churches subsequently surged, especially in the country's south, traditionally Egypt's Christian heartland.
Why are Coptic Christians being persecuted by ISIS?
ISIS is trying to stoke conflict between various groups in an attempt to undermine stability in Egypt, The Atlantic reported in April.
"ISIS is strategically shifting to attacking Copts as a means of propaganda, as it shows the Egyptian state is unable to protect minorities," journalist Mohannad Sabry told TIME last month.
Timothy E. Kaldas with the Tahrir Institute for Middle East Police, in the same interview with TIME, said, "Many Islamists in Egypt see the Coptic Church as partly responsible for the coup against former Islamist President Mohammed Morsi and have regularly engaged in sectarian incitement against Christians since."
Friday's attack is the third against Christians in Egypt in six months.
In April, twin suicide bombings struck two churches on Palm Sunday. In December 2016, a suicide bombing targeted a Cairo church. The attacks left over 75 dead and scores wounded. ISIS claimed responsibility and vowed more attacks.
Sectarian killings did happen as early as the 1970s, but were mostly sporadic, with the exception of the 1990s. That's when the state fought an Islamic insurgency and Copts faced some retaliation.
On New Years' Eve 2010, a bomb in an Alexandria church killed over 20 people - making it the first major assault with a high death toll in living memory.
Attacks picked up in the aftermath of the army's overthrow of Morsi in 2013.
Pope's call for peace
Pope Francis visited Egypt in late April and paid tribute to the victims of the December bombing at Cairo's St. Peter's church.
After the pope's visit, ISIS vowed to escalate the attacks against Christians, urging Muslims to steer clear of Christian gatherings and Western embassies, saying they are targets for the group's followers.
ISIS views the Christian minority as an ally of the West in a war against Islam.
Pope Francis reiterated his call for peace during his meeting with U.S. President Donald Trump at the Vatican. The pair discussed the promotion of peace through "political negotiation and interreligious dialogue, with particular reference to the situation in the Middle East and the protection of Christian communities," according to the Holy See.
The Associated Press contributed to this report.