Egypt resumed airstrikes on militant camps in eastern Libya on Saturday, which were launched after masked gunmen attacked Friday a bus of Coptic Christians south of the Egyptian capital, killing at least 29 people.

Assailants in three pick-up trucks attacked the bus as it was heading for the Saint Samuel Monastery in Minya province, more than 200 kilometers (120 miles) from Cairo, before fleeing, the interior ministry said. It was the latest attack on Copts after Daesh terrorists bombed three churches in December and April, killing dozens of Christians.

State television reported Friday six airstrikes against "terror camps in Libya", specifying that training camps were hit in the eastern Libyan city of Derna. Witnesses there reported four strikes by a single aircraft.

President Abdel Fattah al-Sissi, in a televised address, said Egyptian forces had hit a militant training camp in retaliation.

"Egypt will not hesitate in striking terror camps anywhere, either inside (the country) or outside it," Sisi said.

A spokesman for the pro-Al-Qaeda Majlis Mujahedeen Derna, which controls the city, said the Egyptian air force carried out eight raids on the city without causing casualties.

The Egyptian state television reported Saturday that the military is continuing to carry out airstrikes against militant training camps outside the country. It did not say exactly where the strikes were being conducted.

No group has yet claimed responsibility for attacking the bus.

East Libyan forces led by Khalifa Haftar, a close ally of Sissi's Egypt, said they participated in airstrikes launched.

The East Libyan air force's media office said in a statement that the strikes had targeted forces linked to al-Qaeda at a number of sites, and would be followed by a ground operation.

A resident in Derna told Reuters they had heard four powerful explosions, and that the strikes had targeted camps around Derna used by fighters belonging to the Majlis al-Shura militant group.

Derna is one of the cities where east Libyan forces have been trying to gain control from militant groups and other opponents. Haftar's forces have besieged the city and launched occasional air strikes.

Derna has a history of militancy and is where Daesh set up its first presence in Libya in 2014. However, the terrorist group was later chased from the city by local fighters and rival militants from the Majlis al-Shura group.