Cairo - Egypt's President Abdel Fattah El-Sisi has called a meeting of security officials after gunmen attacked a group of Coptic Christians travelling to a monastery in southern Egypt on Friday, killing 28 people and wounding 25 others. Health Ministry officials said many children were among the victims. The Ministry Cabinet said the attackers will not succeed in dividing the nation. Eyewitnesses said masked gunmen first stopped the two busloads of Christians then opened fire on them. Another vehicle was also fired at. Local television channels showed a bus apparently raked by gunfire and smeared with blood. Clothes and shoes could be seen lying in and around the bus. There was no immediate claim of responsibility for the attack, which came on the eve of the holy month of Ramadan. This attack followed a series of church bombings claimed by Islamic State. Muslim leaders condemned the killings. The Grand Imam of Al-Azhar, Egypt's 1,000-year-old center of Islamic learning, said the attack was intended to destabilize the country. "I call on Egyptians to unite in the face of this brutal terrorism," Ahmed al-Tayeb said from Germany, where he was on a visit. The Grand Mufti of Egypt, Shawki Allam, condemned the perpetrators as traitors. The Coptic church said it had received news of the killing of its "martyrs" with pain and sorrow. The attack took place on a road leading to the monastery of Saint Samuel the Confessor in the province of Minya, which is home to a sizeable Christian minority. An Interior Ministry spokesperson said the unidentified gunmen had arrived in three four-wheel-drive vehicles. Security forces have launched a hunt for the attackers, setting up dozens of checkpoints and patrols on the desert road. Coptic Christians, whose church dates back nearly 2,000 years, make up about 10% of Egypt's population of 92 million.