The group of Coptic Christians was on a bus en route to a monastery in Minya, central Egypt when they were shot.
At least 28 people have been killed after masked gunmen opened fire on a bus in central Egypt, the governor of Minya province, Essam Al Bedaiwy, said. A further 22 have been wounded.
The bus was transporting a group of Coptic Christians as they were driving to a monastery in Minya, which is about 245 kilometres south of Cairo, Bedaiwy said.
The group was travelling in two buses and a truck through the province, which is home to a sizeable Christian minority, he said.
Eyewitnesses said the Copts were attacked as they were going to pray at the monastery of Saint Samuel the Confessor in the western part of the province. They said masked men stopped the vehicles on a road leading to the monastery and opened fire.
The assault happened while the bus was travelling on a side road in the desert leading to the remote monastery.
Security officials quoted witnesses as saying they saw between eight and 10 attackers dressed in military uniforms and wearing masks. The victims were en route from the nearby province of Beni Suef to visit the monastery.
Security and medical officials, speaking on condition of anonymity because they were not authorised to talk to reporters, said the death toll stood at 28 but feared it could rise. According to Copts United news portal, only three children survived the attack. It was not immediately known how many of the victims were children.
Arab TV stations showed images of a badly damaged bus along a 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.
Ambulances are seen parked around the bus and bodies are lying on the ground, covered with black plastic sheets. Another video purported to show about 10 bodies of mature men lying on the sand on the side of the road with pools of blood around them. Children hysterically screaming could be heard in the background.
There was no immediate word from the government on how it intends to stop similar attacks from taking place, but it is likely to heighten security around churches, monasteries, schools and annual pilgrimages to remote Christian sites across the country.
On Wednesday, Egypt blocked access to nearly two dozen websites it said were sympathetic to militants or spreading their ideology.
"The growing number of these terror attacks is not at all reassuring," Father Rafic Greiche, spokesman for the Egyptian Catholic church, told a local television station.
El-Sissi calls meeting
Egypt's President Abdel-Fattah el-Sissi called for a meeting with top aides to discuss Friday's attack. Last month, he declared a three-month state of emergency following twin suicide bombings that struck two churches north of Cairo on Palm Sunday.
Egypt's Coptic Christians, who make up as much as 10 percent of the country's 90 million population, have suffered numerous attacks in recent years. In April, a bomb blast at a Coptic church in Tanta killed 27. Another 11 were killed in an attack in Alexandria.
About 70 have been killed in the bomb attacks on churches in the cities of Cairo, Alexandra and Tanta since December. Responsibility for these attacks were claimed by Daesh. There was no immediate claim of responsibility for the latest attack.
Late last month, Pope Francis visited Egypt, in part to show his support for Christians in this Muslim majority Arab nation following the December and April attacks.
During the trip, Francis paid tribute to the victims of the December bombing in Cairo's St. Peter's church, located in close proximity to Cairo's St. Mark's cathedral, the seat of the Coptic Orthodox Church.
Following the pope's visit, Daesh vowed to escalate attacks against Christians, urging Muslims to steer clear of Christian gatherings and Western embassies, saying they are targets for the group's followers.
Condemnation of the latest attack came from several quarters.
Lebanon's militant Hezbollah group condemned the attack saying it "is a new crime added to the criminal record of a murderers' gang."
Both Hamas and Israel also condemned the attack. Hamas apokesman Fawzi Barhoum in a statement Friday called the shooting "an ugly crime," of which "the enemies of Egypt" are the only beneficiaries.
Prime Minister Benjamin Netanyahu's office issued a statement Friday sending "condolences from the Israeli people to the Egyptian people and to President el-Sissi."
It said "terrorism will be defeated quicker if all countries act together against it."