Masked gunmen attacked a group of Coptic Christians as they were driving to a monastery south of Cairo on Friday, killing 26 and wounding 26, the governor of Egypt's Minya province, Essam al-Bedaiwy, said.
The group was travelling in two busses 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.
Coptic Christians, who make up about 10 per cent of Egypt's population of 92 million, have been the subject of a series of deadly attacks in recent months.
About 70 have been killed in bomb attacks on churches in the cities of Cairo, Alexandria and Tanta since December.
Those attacks were claimed by Islamic State. There was no immediate claim of responsibility for Friday's attack