A Libyan transport plane crashed shortly after takeoff on Sunday at an airfield near El Sharara oilfield, killing three people, the National Oil Corporation (NOC) said.

The military C-130 plane had been chartered by Akakus Oil, which operates Sharara, and had delivered 18 tonnes of catering and maintenance supplies to the southwestern field.

The two pilots and a flight assistant were killed in the crash, the NOC said. A fourth crew member was flown to the capital, Tripoli, for medical treatment.

The plane crashed and exploded in the desert about 2 km away from the oilfield’s facilities.

Akakus was forced to charter the aircraft due to road closures and the security situation, with a road leading to the oil field blockaded, NOC said.

NOC said the circumstances of the crash were being investigated.

Sharara is seen as crucial to helping Libya’s economic recovery but output has been repeatedly disrupted due to blockades by armed groups, protests and other security problems.

The field is currently producing more than 300,000 barrels per day, an engineer working at the field said.