Two police officers say four others were wounded in the attack this morning in the town of Taji. The militants fled the area after a brief clash without suffering casualties.
A health official confirmed the casualty figures. All officials spoke on condition of anonymity as they were not authorised to release information.
Taji is a former insurgent stronghold, located about 20 kilometres north of the Iraqi capital.
The attack followed a spike in violence last week that left nearly 300 people killed. Alarmed by a nationwide deterioration in the security situation, Iraqi Prime Minister Nouri al-Maliki ordered a reshuffle in senior military ranks.