The explosion happened at around 10:00 local time. Interior minister Magdi Abdel-Ghaffar and Cairo's security chief both inspected the scene, according to local media. Egypt's Coptic Christians make up about 10 percent of the country's population. St Mark's Cathedral is the headquarters of the country's Orthodox Church, and the home of its leader, Pope Tawadros II. On Saturday, six policemen were killed when a bomb exploded on a main road leading to the pyramids at Giza. The explosion, at a police checkpoint, was the deadliest attack on security forces in Cairo in over six months. A recently formed militant group called Hasm said it carried out the attack. Egypt's Coptic Christian minority have complained of discrimination in the mostly Muslim nation. Two people were killed outside St Mark's cathedral in 2013, when people mourning the death of four Coptic Christians killed in religious violence clashed with local residents. In February this year, a court sentenced three Christian teenagers to five years in prison for insulting Islam. The teenagers had appeared in a video, apparently mocking Muslim prayers, but claimed they had been mocking the Islamic State group following a number of beheadings.