A single F-16 Fighting Falcon aircraft that crashed Wednesday night in southern Arizona was being flown by an Iraqi pilot who has been training in the U.S. for four years, an official said Thursday.

"We have no word yet on his fate or the reason behind the crash," Brig. Gen. Tahseen Ibrahim, a spokesman for the Iraqi defense minister, told The Associated Press. "We are in contact with the Americans to get more details."

Ibrahim confirmed the pilot is Brig. Gen. Rafid Mohammed Hassan but said the pilot's fate still is not known. He said the rescue operation is difficult because the plane hit a gas pipeline in a rural area.

Hassan was the only person aboard when the plane went down during a Wednesday night training mission with the Arizona Air National Guard's 162nd Wing, the Guard said in a statement. It did not release further information about the pilot.

Angel Ortega, of Douglas, said he heard a loud explosion and initially thought it was a crack of thunder before seeing smoke and fire.

Rescuers were sent to the crash site 5 miles east of Douglas Municipal Airport, according to a Guard statement. Douglas is about 120 miles southeast of Tucson.

The plane ruptured a gas line and sparked a fire that covered about 400 yards, Cochise County sheriff's spokeswoman Carol Capas told the Arizona Daily Star. Once the flames are extinguished, officials will assess the damage.

The Guard's 162nd Wing conducts international F-16 pilot training from Tucson International Airport as well as reconnaissance missions from Davis-Monthan Air Force Base, according to its website.

A board is expected to be appointed to investigate the incident.

U.S. Rep. Martha McSally, R-Ariz., said Thursday that her thoughts are with the pilot, his family and emergency responders.

"Instances like this remind us that those who wear the uniform put their lives on the line every day, and deserve our constant gratitude," she said in a statement.

The Associated Press contributed to this report.