A bomb exploded Sunday morning at a crowded bus station south of Baghdad, killing at least two people and injuring four, police reported. The device detonated as passengers were boarding a bus in Hillah, a predominantly Shiite city about 95 kilometers south of Baghdad, police Capt. Muthana Khalid said. The vehicle was destroyed in the blast. Sunday was the first day traffic was allowed as usual in Hillah after the strife-prone region was placed under an extraordinary daylight curfew to curb a deadly wave of sectarian violence unleashed by the bombing of a revered Shi'ite shrine in Samarra four days ago. A vehicle ban remained in effect in Baghdad and its suburbs, but traffic restrictions were lifted in three surrounding provinces including Babil, where Hillah is located.