US and Iraqi officials say, two US soldiers have been killed when an Iraqi soldier opened fire on them during a training exercise in northern Iraq. The incident happened at al-Ghazlani training camp in the city of Mosul. It was the final drill to showcase US efforts in training Iraqis before next week's visit by US and Iraqi generals. Separately, a US soldier was killed in central Iraq. Attacks by Iraqi soldiers or police against US troops in northern Iraq are rare but not unprecedented.