Reuters quoted witnesses as saying it was hit by a rocket near the town of Mishada, which the military called an area "known for terrorist activity."
Three insurgent groups, including the Al-Qaeda-affiliated Mujahideen Council, issued separate claims. The authenticity of the statements could not be verified.
Meanwhile, Iraq's election commission annulled results from 227 ballot boxes due to fraud during the 15 December parliamentary vote. But it said this would have little effect on results already announced.
According to Reuters, the Shi'ite alliance will have about three-fifths of the parliament seats. Sunni and Kurdish parties will have about a fifth each.
Officials said the final results would be published on 20 January.
(Reuters, AP, AFP)
The Multinational Force in Iraq on December 15, 2005, released official images of the voting in the legislative elections. To view a slideshow of their photographs, click on the image.
To see RFE/RL's special webpage about the election, click here.