Attacks across Iraq on Monday targeted commercial areas and Iraqi security forces, killing at least 15 people and wounding dozens, officials said.

The deadliest attack was in the southern Shiite city of Najaf, about 160 kilometers (100 miles) south of Baghdad, where a parked car bomb ripped through a commercial area, killing six people, said Maj. Gen. Emad al-Taie. That attack also wounded 13 people, said al-Taie, the provincial police chief.

Iraq is going through its worst surge in violence since the peak of the sectarian strife in 2006 and 2007, when the country was on the brink of civil war. The U.N. says 8,868 people were killed in 2013. […]