KHARTOUM – An aerial attack struck two trucks carrying World Food Programme (WFP) food assistance in South Kordofan, killing one driver, the U.N. agency said on Sunday.

WFP said the contracted trucks were traveling from Dilling to Kadugli in the early hours of Oct. 3 and were clearly marked as humanitarian vehicles when they were hit.

The agency said one driver was killed in the attack and expressed condolences to his family, friends and colleagues.

WFP said it was still gathering information about the circumstances of the incident, including the extent of damage to the food cargo.

The agency did not identify who carried out the attack.

WFP called for a prompt and impartial investigation and said anyone responsible for violations should be held accountable.

The attack came one day after another WFP truck struck an explosive device in Dilling after delivering life-saving food assistance, according to the agency.

WFP urged all parties involved in the fighting to comply with international humanitarian law, protect civilians and civilian infrastructure, and ensure the safe and unhindered movement of humanitarian personnel and supplies.

The agency said the incidents highlighted the increasingly difficult security environment facing aid workers in Sudan as they deliver assistance to communities affected by the war.

WFP said it remained committed to delivering life-saving assistance to millions of people across Sudan who depend on humanitarian support.