TEHRAN, Iran (AP) — An Iranian news agency says one of the country’s F-4 fighter jets has crashed in southern Iran and that the two pilots on board were killed.

The report by the semi-official ISNA news agency says the aircraft went down near a lake, shortly after taking off from a military air base in Shiraz around noon on Tuesday. Shiraz is 680 kilometers (420 miles) south of the capital, Tehran.

Gen. Hossein Mohammadi, a provincial military chief, says an investigation is underway at the scene of the crash.

The plane was also used for training but the purpose of Tuesday’s flight was not immediately clear.

Iran’s air force has an assortment of U.S.-made military aircraft, including F-4s, purchased before the 1979 Islamic Revolution. It has also Russian-made MiG and Sukhoi planes.

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