Al-Sumaria news website quoted a security source in the province as saying that the attackers detonated a bomb in al-Mustafa Mosque, located on a road between the cities of Kirkuk and Tikrit.
The source, who spoke on condition of anonymity, said security forces immediately arrived at the scene and started their investigations into the attack.
The source also said Daesh (ISIL or ISIS) militants are believed to have been behind the attack.
Iraqi army and popular forces fully liberated the Arab country from Daesh in December 2017.
However, the group’s remnants continue to carry out terrorist attacks and suicide bombings in different parts of Iraq.