Egyptian officials have disclosed that the gunmen responsible for the massacre at a mosque in Sinai carried the flag of the Islamic State terror group.
A bomb exploded at the Al-Rawdah Mosque in Bir al-Abed, north Sinai on Friday as prayers were finishing, and dozens of masked gunmen waiting outside opened fired on those who were trying to escape.
Earlier reports have indicated that at least 235 people were killed in the attack, but the death toll has since risen to 305, which included at least 27 children.
Egypt's chief prosecutor, Nabil Sadeq, said 25–30 militants had stationed themselves at the mosque's main door and 12 windows before they opened fire on the worshippers.
According to the BBC, the attackers set fire on parked vehicles in the vicinity to block access to the mosque, fired on ambulances trying to help the victims.
While no group has taken credit for the massacre, it was reported that the gunmen were carrying an ISIS flag. It is believed that the attack was carried out on a Muslim place of worship because it was frequented by Sufis, a sect considered by many Islamic radicals to be heretical.
President Abdul Fattah al-Sisi has vowed to respond with "utmost force," and the Egyptian military has stated that air strikes were already being carried out on "terrorist" targets.
"What is happening is an attempt to stop us from our efforts in the fight against terrorism," the president said in a televised address hours after the attack.
"The armed forces and the police will avenge our martyrs and restore security and stability with the utmost force," he continued.
Another 128 people were wounded in the attack that has been seen as one of the worst terrorist incidents in Egyptian history. Over 50 ambulances had transported the victims from the mosque, about 25 miles west of the city of Arish, to nearby hospitals.
Islamic militants have stepped up attacks in Sinai after Islamist President Mohammed Morsi was toppled in July 2013 following mass anti-government protests.
Since that time, hundreds of police, soldiers and civilians have died in attacks, which were mostly carried out by the ISIS-affiliated group known as the Sinai Province.
The group has previously claimed responsibility for the bombing of a Russian plane carrying tourists in Sinai in 2015, killing 224 people on board.
North Sinai has been under a state of emergency since October 2014, when 33 security personnel died in an attack claimed by the Sinai Province group.
The terror organization reportedly aims to take control of the Sinai peninsula in order to turn it into an Islamist province run by ISIS.