Twenty-one people were killed and 26 others wounded in violent attacks across Iraq on Wednesday, police said. In the northern province of Nineveh, a suicide car bomb struck an army checkpoint in the provincial capital of Mosul, some 400 km north of Baghdad. The attack killed three soldiers and a civilian, and injured another five soldiers. Also in Mosul, three roadside bombs killed two policemen and wounded three. The police in Mosul clashed with gunmen for more than an hour Wednesday near the south of the city, killing three of them. Police also found two male bodies near the city of Qaiyara, some 40 km south of Mosul. They had bullet holes in their heads and chests. In Salahudin province, gunmen attacked a police station in Tal al-Dhahab area, some 80 km south of the provincial capital Tikrit. The station chief and two policemen were killed. Another two policemen were injured. Salahudin is a Sunni-dominated province. Its capital Tikrit, some 170 km north of Baghdad, is the hometown of former Iraqi leader Saddam Hussein. In Iraq's eastern province of Diyala, a roadside bomb struck a bus near the provincial capital of Baquba, some 65 km northeast of Baghdad. Four people were killed and five others wounded. In northeast Baquba, gunmen killed a civilian and wounded another. Another four people were wounded in the south of the city, when a sticky bomb attached to their car was detonated. In Baghdad, gunmen shot dead two civilians in two attacks using silenced weapons. The city also saw four civilians wounded by two roadside bombs. In the town of Mahmoudiyah, some 30 km south of Baghdad, a sticky bomb injured another two soldiers. Iraq is witnessing its worst violence in recent years. The UN Assistance Mission for Iraq says a total of 8,868 Iraqis, including 7,818 civilians and policemen, were killed in 2013, the highest annual death toll in years.