Dr Mohammed al-Saidi from Jilla general hospital said: "After the attack, he was brought to the Hilla hospital and doctors started an emergency operation on him. But he died in five minutes."
Fears of clashes
An indefinite curfew on Hilla was immediately announced due to fears of further clashes. Local people were seen firing their guns into the air as a sign of mourning, AFP reported.
US commanders in the area had praised al-Mamoori for his attempts to improve security in Babil province.
Al-Mamoori was planning to meet US-led troops later on Sunday, officials said. The bomb attack has not been linked to the meeting.
Babil is a predominately Shia province which has seen an increase in attacks this year, allegedly by Sunni fighters. One bomb attack in March killed 92 people.
Many attacks have been aimed at Shia pilgrims travelling through the region.