MOSUL, Iraq (Reuters) - Two U.S. soldiers were killed and a third injured when an Iraqi soldier opened fire on U.S. troops during training in the northern city of Mosul on Saturday, the U.S. military said.

The incident occurred while U.S. soldiers were training Iraqi security forces at al-Ghazlani U.S. military camp in southern Mosul, 390 km (240 miles) north of Baghdad, the U.S. military said.

“Two U.S. service members were killed by small arms fire when an Iraqi soldier attacked them at the Ghazlani Training Center located south of Mosul at approximately 8:30 a.m. Saturday,” the U.S. military said in a statement.

It said the Iraqi soldier who had opened fire was killed during the incident. A third U.S. service member was wounded, the U.S. military said.

“Until now, we don’t have any information on why the two Iraqi soldiers opened fire,” a senior Iraqi police official, who declined to be named, said.

Separately, another U.S. service member was killed while conducting operations in central Iraq, the U.S. military said in a separate statement on Saturday. It gave no further details and did not specify where the incident occurred.

Fewer than 50,000 U.S. troops remain in Iraq since the United States officially ended combat operations last August. The remaining soldiers are focused on advising and assisting Iraqi security forces as they take the lead in the fight against a weakened yet resilient insurgency.

Bombings and attacks remain a daily occurrence in Iraq, although violence has fallen since the height of sectarian fighting in 2006-7 unleashed by the 2003 U.S.-led invasion.

Mosul remains one of the most dangerous cities in the country, where Iraq is still fighting a stubborn Sunni Islamist insurgency.