Earlier, an explosives-rigged bicycle blew up near an army recruiting center in a city south of Baghdad, killing at least 12 people.
Violence across Iraq has spiked in recent days, with more than 200 people killed since Sunday in clashes, bombings or shootings — despite U.S. and Iraqi officials' claims that a new security operation in the capital has lowered Sunni-Shiite killings there, which had risen in June and July.
One senior commander said, "The bad guys are trying to make a statement," reports CBS News correspondent Mark Strassmann. Coalition commanders say this mayhem can be brought under control — and that given time, Iraqi forces will be able to do it on their own.
"I don't have a date," said Gen. George Casey, the top U.S. commander in Iraq, "but I can see over the next 12 to 18 months, I can see the Iraqi security forces progressing to the point where they can take on the security responsibilities for the country — with very little coalition support."
targeted the Shurja district, where wholesalers use warehouses, stalls and shops to sell food, clothing and house products to other dealers and shoppers. A maze of streets and stalls, it hosts one of Iraq's biggest markets and is usually teeming with vendors selling everything from spices to satellite dishes.
In other developments:
Elsewhere in Baghdad, a Justice Ministry official, Nadiya Mohammed Hassan, was shot and killed along with her driver and bodyguard by gunmen who stopped her car. Three carpet merchants were also killed while being driven to an appointment in a taxi, police said.
A family of five was killed in Buhriz, 35 miles north of Baghdad, when a roadside bomb struck their car.
In the town of Hillah, about 60 miles south of Baghdad, a man posing as a potential army cadet planted the bicycle outside the recruiting center. The bomb exploded as volunteers gathered outside to sign up for the army. Hillah was the site of one of the worst bomb attacks in Iraq, when a suicide car bomber in February 2005 killed 125 national guard and police recruits waiting to take physicals.
Insurgents have often targeted army and police volunteers as they wait outside recruiting stations, as a way to discourage people from joining the security services.
In downtown Baghdad, three police officers were killed and 14 people were injured when twin bombs — including one planted in a car — struck a police patrol as it drove by a line of vehicles waiting in a line for gasoline at a filling station.