For the second time in a matter of days, food aid for starving Ethiopians has been stolen from the World Food Program in northern Ethiopia, the United Nations said Monday.

“On the evening of December 10th, a group of armed actors – believed to be either from the Ethiopian National Defense Forces or an affiliated allied military force – entered the Disaster Risk Management Committee compound in Kombolcha and took 18 WFP trucks by force,” U.N. spokesman Farhan Haq told reporters. “The armed individuals then used the trucks in several locations for their own purposes.”

He said 15 trucks have been returned, but three remain unaccounted for.

“The safety and security of U.N. and partner staff remain our highest priority and we call for the immediate and safe release of our staff, colleagues, and vehicles,” Haq said.

The WFP has informed the federal government and local authorities in the town of Dessie, whom the spokesman said are assisting in the recovery the three trucks. The towns are in the Amhara region of northern Ethiopia, which has seen aid needs skyrocket in recent months.

The U.N. says 3.7 million people in Amhara need humanitarian assistance due to the conflict between federal government forces and the Tigray People’s Liberation Force (TPLF). Fighting has been going on for more than a year, and in July, it spilled over into the neighboring regions of Amhara and Afar.

On December 7 and 8, the U.N. said three WFP trucks were commandeered by military personnel and used for their own purposes. WFP warehouses in Dessie and Kombolcha were also looted, and large amounts of food stocks were taken, including nutritional items for malnourished children.

The U.N. said some of their staff had been held at gunpoint. Aid distribution was suspended following that incident.

A U.N. spokesman said recent “mass looting” in Kombolcha was reportedly carried out “by elements of the Tigrayan forces and some members of the local population.”