The shooting in the province of Minya on Friday, May 26, as the Coptic Christians were traveling on a bus to a monastery, was the latest in a series of attacks by ISIS that have killed more than 100 Copts since December.
The jihadist group claimed in a statement that its fighters "set up a checkpoint" for the Christians as they headed to the monastery, then killing them and setting one of their vehicles on fire.
The interior ministry said masked gunmen in 3 pick-up trucks had attacked the bus as it heading for Saint Samuel monastery in Minya province, more than 200 kilometers (120 miles) south of Cairo, before fleeing.
The attack prompted Egypt to unleash air strikes on jihadist camps in neighboring Libya.
The military published footage of the strikes but declined to say where they took place.
A spokesman for the pro-Al-Qaeda Majlis Mujahedeen Derna, which controls the city in eastern Libya, said the Egyptian air force carried out 8 raids on the city without causing casualties.
The air force loyal to Libyan military strongman Khalifa Haftar, who is backed by Egypt, on Saturday said it had participated in the strikes, describing them as "heavy in casualties".
Majlis Mujahedeen Derna ousted ISIS from Derna in 2015 and also fights Haftar's forces.
The group has no known connections to ISIS in Egypt.
The link between Derna and Friday's attack was not immediately clear, but Egypt has repeatedly expressed concern over militants crossing from Libya to Egypt to conduct attacks.
In a speech on Friday, Sisi said setbacks to ISIS in Syria were driving its fighters to try to relocate to Libya and Egypt's Sinai.
In past attacks, Egypt had usually identified local jihadists as the perpetrators.
Friday's attack followed two suicide bombings of churches in April that killed 45 Copts. In December, a suicide bomber struck a church in Cairo, killing 29 Copts.
ISIS claimed all the bombings and threatened more attacks on the Copts, who make up about 10% of Egypt's population of 90 million.
It has also killed several Christians in North Sinai, forcing dozens of families to flee.
The latest attack drew global condemnation.
"Terrorists are engaged in a war against civilization, and it is up to all who value life to confront and defeat this evil," US President Donald Trump said in a statement.
Pope Francis, who had visited Egypt in April, sent a message to Sisi saying he was "deeply saddened to learn of the barbaric attack". – Rappler.com