Egypt's president says a suicide bomber caused the explosion that killed 24 Christians during Sunday Mass at a Cairo chapel.
President Abdel-Fattah el-Sissi identified the bomber as 22-year-old Mahmoud Shafiq Mohammed Mustafa.
He said three men and a woman have been arrested in connection with the attack at a chapel adjacent to Cairo's St Mark's Cathedral, the seat of the Coptic Orthodox Church.
The president spoke after Health Ministry officials revised down the number of victims to 24, suggesting that the 25th body belonged to the bomber.