MOSUL, Iraq (Reuters) - Two US soldiers were killed and a third was injured when two Iraqi soldiers opened fire on US troops during training in the northern city of Mosul on Saturday, Iraqi army sources said. The incident occurred while US soldiers were training an Iraqi military unit at al-Ghazlani US military camp in southern Mosul, 390 km (240 miles) north of Baghdad, they said. According to available information, two American soldiers were killed today during a shooting at a training session inside al-Ghazlani military camp. Two Iraqi soldiers suddenly opened fire at the American soldiers, an Iraqi military colonel in Mosul, who declined to be named, said. The US military said in a statement two US service members were killed and one was wounded while conducting operations in northern Iraq, but did not give further details. Until now, we dont have any information on why the two Iraqi soldiers opened fire, a senior police official said. The police and army sources both said the two Iraqi soldiers had been arrested, although it was unclear if they were being held in Iraqi or US custody. Another Iraqi military colonel said an initial report indicated that one of the Iraqi soldiers had also been killed. We have an initial report that one of the Iraqi soldiers who opened fire was killed by American forces, but its not confirmed yet, he said. Separately, another US service member was killed while conducting operations in central Iraq, the US military said in a statement on Saturday. It gave no further details and did not specify where the incident occurred.