BAGHDAD, Aug. 20 (Xinhua) -- One soldier of a coalition led by the United States to fight Islamic State (IS) militants was killed and several others injured on Monday in an aircraft crash in Iraq, the U.S. military said in a statement.

The incident took place while the aircraft was "conducting a partnered counterterrorism mission in support of Operation Inherent Resolve (OIR), which is the U.S. military's operational name for the military intervention against IS extremist militant group in Iraq and Syria, the OIR statement said.

"All personnel were recovered by coalition forces immediately following the incident, and three were evacuated for further treatment," the statement said without giving details about the kind of the aircraft.

It was unclear why and where the aircraft went down, but the statement said that "there are no indications the crash was caused by hostile fire. The incident is under investigation."

Over 5,000 U.S. troops have been deployed in Iraq for supporting and training the Iraqi forces despite the territorial defeat of the extremist IS militants in the country late last year.