AP — An Iranian fighter jet went down on Wednesday in the north of the country, near the border with Azerbaijan, Iran’s state television reported. The fate of the pilot was not immediately known.

The TV reported that the crash happened in the Sabalan mountainous region and that rescue teams and three search helicopters were looking for the pilot who was said to have contacted his base following the crash.

The fighter jet was a recently overhauled MiG-29. The pilot was test flying the plane and had taken off from the Tabriz air base in northwestern Iran earlier in the day.

An investigation was underway into the cause of the crash, the report also said.

Iran’s air force has an assortment of U.S.-made military aircraft purchased before the 1979 Islamic Revolution. It also has Russian-made MiG and Sukhoi planes. Decades of Western sanctions have made it hard to maintain the aging fleet.