May 26 (UPI) -- Gunmen opened fire on a bus carrying Coptic Christians in Egypt's Minya province Friday, killing nearly 30 people and injuring many others, authorities said.
The bus was heading toward the Monastery of St. Samuel on a road near El Edwa city, about 140 miles south of Cairo, when the shooting started.
Officials said the attackers were dressed in military fatigues and posed as security officers when they ordered the bus to stop. They then pulled the riders off the bus, separated the men from women and children and forced them to pledge allegiance to Islam. When they refused, the militants began shooting.
Authorities said at least 28 of the Christians were killed and more than two dozen were injured.
The Copts United media outlet said the militants had been hiding on a hill overlooking the road.
Egyptian President Abdel Fattah el Sisi promised that the attack "will not go unanswered."
"By the time they killed half of the people, the terrorists saw cars coming in the distance and we think that that is what saved the rest," Egyptian lawmaker Magdy Malek said after visiting victims of the attack Friday. "They did not have time to kill them all. They just shot at them randomly and then fled."
On Sunday, Egyptian Attorney General Nabil Sadik said he referred 48 suspected Islamic State militants to a military court over the bombing of Coptic churches.
The Islamic State took responsibility for bombing the St. Peter and St. Paul Church in Cairo's al-Abbasiya neighborhood in December and also took credit in April for targeting the Saint Mark's Church in Alexandria and the Mar Girgis church in Tanta.
More than 70 people died in the attacks targeting the Coptic churches. Following the attacks in April, Egyptian President Abdul Fattah al-Sisi declared a three-month state of emergency.