The truck, loaded with vegetables and fruits, was parked in the southwestern, Shi'ite-dominated Amil neighbourhood, a police officer said.
Monday's explosion also wounded at least 25 civilians and damaged about 20 cars, he added.
A medical official confirmed the casualty figures.
The attack comes as Iraqi government forces and allied Shi'ite and Sunni fighters, backed by airstrikes from the US-led international coalition, are battling Islamic State militants to retake key cities and territory in northern and western Iraq.
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In its blitz last year, IS captured large swaths of land in the country's north and west, along with nearly a third of neighbouring Syria.
No group immediately claimed responsibility for Monday's bombings.
