BAQUBA, Iraq, Jan. 19 (Xinhua) -- Four people including an Islamic State (IS) militant were killed Friday in bomb and gunfire attack in Iraq's eastern province of Diyala, a provincial official and a security source said.

The deadliest attack occurred in the mountainous Himreen area when IS militants ambushed a group of paramilitary Sunni tribal fighters in the northern part of the province, leaving two paramilitary fighters and an IS militant killed, said Abdul-Khaliq al-Azzawi, a member of the provincial council's security committee.

Reinforcement fighters of the paramilitary unit carried out an operation in the area and destroyed four IS hideouts, Azzawi told Xinhua.

In another incident, unknown gunmen shot dead a government employee that works for the provincial health department when they broke into his family's orchard in Shirween area in the northeast of the provincial capital Baquba, some 65 km northeast of Baghdad, a provincial police source told Xinhua.

Despite repeated military operations in the ethnically-mixed Diyala province, remnants of IS militants were still hiding in rugged areas near the border with Iran in eastern part of the province, as well as the sprawling areas in northern and western Diyala.

On Dec. 9, 2017, Iraqi Prime Minister Haider al-Abadi officially declared full liberation of Iraq from IS militants after Iraqi forces recaptured all the areas once seized by the extremist group.

Nevertheless, small groups and individuals of IS militants are still capable of carrying out attacks from time to time.