ISIS-affiliated militants claimed an attack on Egypt's security forces in the Sinai Peninsula, which killed 13 on Saturday, Al Arabiya News Channel's correspondent reported. The correspondent said the ISIS-affliated Wilayat Sinai claimed the attack which targeted the security forces near Arish, the largest city in Sinai. The English language and state-own Ahram Online daily said on its website "unidentified gunmen have attacked a security checkpoint in the North Sinai city of Arish." Citing sources, Ahram Online said "ambulances were not able to reach the site of the attack in the El-Safa neighborhood." Meanwhile, a security source told the local Youm7 website that a blast has taken place in Sheikh Zuweird, a town in North Sinai, after "terrorist elements" fired mortal shells at police. The source said army and police forces are now patrolling the area. Militants have regularly attacked security forces in the peninsula since Islamist president Mohamed Morsi was ousted amid mass street protests in July 2013. Militants say their attacks are in retaliation for a government crackdown targeting Morsi supporters that has left hundreds dead and thousands imprisoned. The authorities say hundreds of policemen and soldiers have been killed in attacks, mainly in North Sinai, since 2013, although there have also been attacks in the Nile Delta and in Cairo.