The bomb was planted near al-Rowda mosque in Al-Arish and went off during prayers.
The gunmen opened fire on worshippers during the Friday prayers and also on the people fleeing out from the mosque after the explosion, the sources said.
Khaled Megahed, Health Ministry spokesperson said that 75 people were injured during the attack.
However, no group has claimed responsibility for the attack.
Egypt's North Sinai has witnessed many violent attacks by militants since the January, 2011 revolution that toppled former president Hosni Mubarak.
Over 700 security personnel have been reported killed since then.
The military has launched security campaigns in the area, arrested suspects and demolished houses that belong to terrorists, including those facilitating tunnels leading to the Gaza Strip.