The toll of Friday clashes between policemen and supporters of former President Mohamed Morsi in Arish rose to six dead and 17 injured, medical sources at the Arish Hospital told Reuters Aswat Masriya.
One of the deceased is a police conscript, the sources added.
Morsi's supporters attacked Rommana Police Station in Arish's Ber al-Abd, police sources told Aswat Masriya earlier on Friday.
One of the attackers was shot in the chest and is in a critical condition, the source stated.
Army forces took over the police station after all police officers were cleared out of the building.
Supporters of the ousted president opened fire on and hurled petrol bombs at the Civil Defence headquarters in Arish, prompting policemen to retaliate by returning fire.
Witnesses reported hearing huge explosions due to the grenades fired at the Civil Defence headquarters.
In a separate incident, unknown gunmen fired three rocket-propelled grenades at a rest house for North Sinai's governor.
Sinai has suffered a power vacuum ever since an uprising swept autocrat Hosni Mubarak from power in 2011, increasing with the overthrow of Muslim Brotherhood backed Mohamed Morsi.
Morsi supporters took to the street nationwide Friday to denounce the dispersal of pro-Morsi sit-ins in Cairo’s Rabaa Al-Adawiya Square and Giza’s Nahda Square, that left more than 500 dead and at least 2000 injured.
Clashes between the supporters of the ousted president and police on Friday have left tens dead.