A roadside bomb killed six people and wounded 12 Sunday morning in the oil-rich city of Basra in southern Iraq, local officials said.
A police officer in Basra and a morgue official confirmed the death toll from the blast in the city's Maqal area, 340 miles (550 kilometers) southeast of Baghdad.
Another police officer said the bomb hit a bus after it missed a passing U.S. army patrol. He put the death toll at three, but there was no way to immediately reconcile the difference in numbers. Conflicting reports on casualties are common in the immediate aftermath of attacks.
All officials spoke on condition of anonymity because they were not authorized to release information.
Under the 2008 security agreement between the U.S. and Iraq, all American troops must leave Iraq by the end of next December and the U.S. operations will shift to the State Department. There are now fewer than 50,000 U.S. troops in Iraq.
The U.S. troops are not intended to have a combat role, but they still come under attack on an almost daily basis.
Also Sunday, police said someone broke into a local radio station in the Kurdish region of northern Iraq and broke some equipment. It was the second attack on a media outlet in the self-ruled region since thousands of protesters began taking to the streets Feb. 17, taking inspiration from the demonstrations going on across the Middle East and demanding political and economic reforms.
Rahman Gharib, who heads a center defending journalists in the Kurdish region, said the radio station in Kalar, called Voice, that was vandalized Sunday is an independent station established by two young journalists about two years ago. He did not know who was responsible for the attack but said the station had been aggressively covering anti-government demonstrations in the city. Two people have been killed in the demonstrations so far.
Gunmen burst into a Kurdish television station in Sulaimaniyah on Feb. 20, shooting up equipment and setting fire to the building, apparently in retaliation for footage it aired earlier in the week of a deadly protest.
While the three provinces that make up the Kurdish region have enjoyed relative stability and prosperity compared to the rest of Iraq, many Kurds chafe at the tight hold that the region's two main political parties retain on the economy and politics.
Associated Press writer Yahya Barzanji in Sulaimaniyah contributed to this report.