A car bomb exploded in a business district of central Baghdad on Tuesday morning, and a police officer said at least seven people were killed and 16 wounded.
The blast, which occurred near a cinema, sent a huge plume of black smoke up into the sky, and an Associated Press reporter at the scene saw rescue workers carrying bloodied bodies away on stretchers.
A police officer with the Interior Ministry said on condition of anonymity that at least seven people were killed and 16 wounded by a suicide car bomb that exploded just as a U.S. military convoy of Humvees and armored vehicles was passing. Al-Arabiya television confirmed those casualty figures.
The U.S. military said a car bomb attack had occurred in the area but provided no other details.
Firefighters and ambulances raced to the scene, where at least five heavily damaged vehicles were burning in al-Nasr Square, a main intersection of shops, offices and apartment buildings, the AP reporter said.
Police fired warning shots in the air to force away a crowd of people gathering at the scene and closed the area, the reporter said.
About an hour after the al-Nasr Square blast, another loud explosion occurred several miles (kilometers) away on the other side of the Tigris River in Baghdad.
Black smoke could be seen rising into the sky behind the U.S.-protected Green Zone, where Iraq's parliament meets and many embassies are located. The cause of the blast was not immediately known, the U.S. military said.
On Saturday, two car bombs exploded a few hundred meters (yards) from the site of the al-Nasr Square blast, hitting an American security company convoy and killing at least 22 people - including two Americans. That attack also wounded at least 36 Iraqis, three Americans, an Australian and an Icelander.