Police officials say that today evening blast took place in the Shiite district of Sadr city, killing seven people and wounding 20 others.
Hospital officials confirmed the death toll. All officials spoke on condition of anonymity because they were not authorized to speak to the media.
Iraq has seen a spike in violence since last year, with the death toll climbing to its highest levels since the worst of the country's sectarian bloodletting between 2006 and 2008.
Today's attack came ahead of Iraq's first parliamentary elections since the US troops' withdrawal in late 2011. More than 9,000 candidates will compete for 328 seats.