At least 36 people were wounded in the assaults, which involved car bombs and mortar rounds in the town of Al-Arish, in North Sinai, the sources told the Egyptian website. The army is battling an Islamist insurgency in North Sinai that has spiked since the 2013 ouster of Islamist President Mohamed Morsy.
Suspected militants carried out consecutive attacks on the headquarters of the North Sinai security directorate in Al-Arish, a nearby army base, a hotel and several security checkpoints, state TV and the Ahram Arabic news website reported.
Blasts cracked walls and shattered windows of surrounding buildings. Troops combed the area in search of suspects.
The country's most active Jihadist group, Ansar Beit Al-Maqdis, said via Twitter that it was behind the assaults. In November, the Sinai-based group pledged allegiance to ISIS, which has seized swaths of Syria and Iraq.
The office of flagship newspaper Ahram in Al-Arish, located near the targeted police building, was slightly damaged in the attack, office head Ahmed Selim said.
The building was vacant at the time because of a dusk-to-dawn curfew imposed in North Sinai late in October, after deadly militant attacks that killed 31 soldiers earlier in the month in what was considered the worst violence on Egyptian troops in recent times.
One army member was killed and another wounded in a separate attack on a security checkpoint in the North Sinai border town of Rafah.
The military said the violence came in response to the "successful" security campaign against militants in the restive province. The statement did not include a death or injury toll.
Egypt's army has struggled to crush the militant insurgency in the peninsula, which at times has expanded to mainland cities, including Cairo.
Militants have mainly targeted police and troops, killing hundreds in the last 18 months.
Ansar Beit Al-Maqdis has claimed responsibility for some of the deadliest attacks.
The violence has prompted the army to demolish houses and clear residents in Rafah in an attempt to establish to a buffer zone aimed at deterring militant infiltration and arms smuggling.