Unidentified gunmen attacked three checkpoints and the central security sector in Arish, the capital of Sinai, on Saturday, while policemen fired back at the attackers with no reports of injuries. Security officials and witnesses told Middle East News Agency (MENA) that masked gunmen in vehicles attacked the checkpoints early morning in Al-Masoura and Al-Safa areas in Rafah northern Sinai, Al-Mazra\'a in Arish, and the central security sector in Al-Ahrash, Rafah. Meanwhile, armed groups have attacked eight police and army security checkpoints in Arish, Rafah, and Sheikh Zuweid northern Sinai, using mortars and RPGs on Friday. Moreover, the armed groups besieged a central security camp in Al-Ahrash firing rockets from the surrounding mountains towards the camp, and also attacked Al-Arish Airport with heavy weapons. Elsewhere, security forces in Alexandria arrested 52 people involved in Sidi Jaber clashes between anti-Morsi protestors and supporters of the ousted president. Among the arrested were two snipers accused of hiding on the roofs of buildings carrying hand grenades. Officials in Alexandria intelligence said today that security forces are still searching Sidi Jaber for those involved in the clashes, adding that the forces are besieging buildings with suspected snipers.