Story highlights 23 others were wounded and some are in critical condition

Men, women and children are among the dead and injured

Cairo, Egypt (CNN) At least 28 people were killed in Egypt after unidentified gunmen opened fire on a bus carrying Coptic Christians in what officials are calling a terror attack.

Ten assailants wearing fatigues and face masks fired on the passengers from three four-wheel drive vehicles on a desolate stretch of desert road, Egypt's Interior Ministry told CNN.

Hours later, Egypt responded with airstrikes against terrorist camps, President Abdel Fattah al-Sisi said in an on-camera statement, according to state-run Nile TV.

The Christians were traveling Friday to a monastery, St. Samuel the Confessor, around 100 km (62 miles) northwest of the city of Minya when they came under fire, the ministry said.

Twenty-three others were injured, some of whom are now in critical condition, Minya Gov. Essam El-Bedewy told Egyptian satellite channel ONTV.