Residents living near Iraq's largest dam say Sunni militants from the Islamic State of Iraq and Greater Syria (ISIS) group have overrun the complex, AP reported.
The residents say the militants stormed the Mosul Dam complex in one hour Thursday.
The dam, north of Iraq's second-largest city of Mosul, lies on the Tigris River, which runs through the capital, Baghdad.
ISIS has fought local Kurdish peshmerga fighters for control of the dam for nearly one week.
At least three residents who live in the area spoke to The Associated Press on condition of anonymity, fearing for their own safety.
The government did not immediately comment on the developments.