The number of Christians killed in an armed attack on buses carrying pilgrims in Upper Egypt’s Minya governorate has risen to 28, with 23 injured, the governor announced on Friday afternoon.

In a phone call interview with local satellite channel ONTV live on Friday afternoon, Minya's governor, Essam El-Bedewy, announced the new death toll, adding that seven of the victims were from El-Minya while the other 21 were from Beni Suef governroate.

Shortly after, Egypt's health ministry confirmed that the death toll had risen to 28. 

The interior ministry said in an official statement that unknown assailants driving three 4x4 wheelers attacked by "firing randomly" at the bus carrying Coptic citizens. 

The ministry added that an official count of the final death and injuries toll was underway.

A cordon was imposed around the site of the attack, with security forces intensifying efforts to catch the culprits, according to the statement. 

The ages of the victims ranged from children to over 60, the bishop of Minya told Egyptian privately owned TV Channel DMC. Many victims were children, and only three children survived the attack, a source from the church told Al-Ahram.

The bishop added that the vehicles attacked included a minibus and two cars. 

Fifteen of the injured were transferred from Maghagha Central Hospital in Minya to Maahad Nasser Hospital in Cairo, sources at Minya's ambulance service told MENA. 

The bishop of Maghagha and Adwa in Minya, Bishop Agathon, said that the funeral service for the victims of the  attack will be held tonight at the Monastery of Garmous in Maghagha.

"We are in pain over violence and evil,” Egypt’s Coptic Orthodox Church said in a statement on Friday afternoon, adding that it was suffering "with the whole nation over the violence and evil that targets the heart of Egypt and our national unity.”

“While we appreciate the fast response by officials in dealing with the event, we hope that necessary procedures are undertaken to avoid such attacks, which damage Egypt’s image and cause Egyptians a great deal of pain,” the statement added.

President Abdel-Fattah El-Sisi called for an emergency security meeting to follow up on the attacks.

In a statement from the presidency, El-Sisi also instructed authorities to take all necessary measures to attend to the injured and arrest the assailants. 

Egypt's Prosecutor-General Nabil Sadek has ordered an extensive investigation to arrest the attackers, Al-Ahram Arabic website reported.

The prime minister and the ministers of health and social solidarity are heading to the attack scene in Minya.

Al-Azhar's Grand Imam Ahmed El-Tayyeb condemned the attack while on a visit to Berlin, saying that "such attacks can never satisfy a Muslim or a Christian." 

Arab and western countries have denounced the attack, expressing their solidarity with Egypt against terrorism.

No group has yet claimed the Minya attack, which is the latest in a series of deadly attacks on Egypt’s Christians.

On 9 April, two suicide bombers targeted St George's Church in Tanta and St Mark's Cathedral in Alexandria, killing and injuring dozens in the deadliest attack against civilians in the country's recent history. A total of 29 people died in the Tanta explosion and 18 in Alexandria.

Egyptian authorities said they have identified the two suicide bombers and the terrorist cells responsible for the attacks.

Cairo imposed a nationwide three-month state of emergency after the bombings, with the option to extend for another three months dependent on a parliament vote.

Coptic Christians make up about 10 percent of Egypt's population of 92 million.