A car bomb detonated near one of the main gates leading into the fortified Green Zone in central Baghdad, killing three foreigners and wounded two others, an interior ministry official said.
Maj. Falah al-Mohammadawi said the blast apparently targeted a convoy of sport utility vehicles leaving the Green Zone, the headquarters of the Iraqi government and US forces in Iraq.
An earlier police report said one police officer was killed and four others wounded in addition to three civilians. The two reports could not be immediately reconciled.
The explosion was followed by small arms fire and billowing black smoke that could be seen across the city.
The blast occurred near the Iranian embassy, about 100 yards north of the Green Zone gate, which is surrounded with blast walls.
On most days in Baghdad at least one car bomb detonates in the city, mostly targeting Iraqi security services or US troops. Direct attacks on the Green Zone are relatively rare.
The initial reports also indicated a suicide bomber detonated the car, but that could not be immediately confirmed.