The attack in the capital's eastern Shiite-dominated New Baghdad neighborhood also wounded at least 38 other people, a police officer said. Police earlier said it was a parked car bomb.
A medical official confirmed the causality figure. All officials spoke on condition of anonymity as they were not authorized to release information.
No group has claimed responsibility for the attack, but it bore the hallmarks of the Islamic State group, which controls key areas in the country's west and north.
The group has recently increased attacks in and around Baghdad as government forces backed by US-led airstrikes have pushed IS back on a number of fronts in recent months, clawing back territory seized by the extremists during their sweep across northern and western Iraq in 2014.
Late Saturday night, suicide attacks targeted security forces in two Baghdad suburbs, killing 14 people and wounded dozens.
A day earlier, a suicide attack on a Shiite mosque in a southwestern suburb killed 13 worshippers and wounded 35 others, a police officer said.