An Iraqi F-16 fighter jet crashed late Wednesday during a training flight in the US state of Arizona, reportedly rupturing a gas line and sparking a large fire.

Emergency crews rushed to the site of the crash about eight miles (13 kilometers) north of Douglas near the border with Mexico, local fire officials said.

US and Iraqi defense officials confirmed that the fighter had been sold to Iraq and was being piloted by an Iraqi. Search teams are looking for the pilot, whose fate is unknown.

The accident happened during an aerial refueling maneuver, a US defense official said.

Washington has agreed to sell 36 F-16 fighter jets to Iraq, and 36 pilots are in the United States for training.

But the sale has been a source of contention, with Baghdad repeatedly complaining that the jets have not been delivered quickly enough.

Insecurity in Iraq, where the Islamic State jihadist group overran major territory last June, has delayed the delivery of the jets, which are expected to give a much-needed boost to Iraq's fledgling air force.

Davis-Monthan Air Force Base in Arizona tweeted that the F-16 went down around 0300 GMT near Douglas local airport, and the status of the pilot is "unknown at this time."

The crash appeared to have ruptured a gas line and started a large fire, The Arizona Republic reported. Images on Twitter showed multiple fires illuminating brush.

Davis-Monthan Air Force Base is some 100 miles (160 kilometers) away from Douglas.