Egyptian security officials say gunmen opened fire, killing two policemen guarding a Coptic church south of Cairo.
The attack occurred in the provincial capital of Minya early on Tuesday as members of Egypt's minority Christian Copts observe Christmas Eve, according to the old, Julian calendar.
The officials say police have cordoned off the area and are searching for the perpetrators. They spoke on condition of anonymity because they are not authorized to talk to media.
Egypt had beefed up security around Coptic churches ahead of Christmas. Christians account for some 10 per cent of the nation's 90 million people and have long complained of discrimination by the nation's Muslim majority.
Attacks against them have also risen since the ouster of Islamist President Mohammed Morsi in July 2013.