The incident, which drew sharp criticism from U.N. officials, occurred Wednesday less than 30 miles north of Galkayo in Somalia's war-torn Mudug region. Official say militiamen set up an illegal checkpoint where 12 WFP trucks in a convoy were forced to stop.

A gunman opened fire on the trucks, shooting one of the drivers, who died later in the hospital. The truck driver is the second to be killed in the last year while attempting to deliver aid. In February another truck driver leading a convoy in southern Somalia was gunned down by militiamen, the United Nations reported.

"We condemn this senseless killing and, once again, urge all parties to ensure the safe passage of humanitarian staff and cargo across the country," Peter Goossens, WFP Somalia country director, said in a statement.

The deteriorating security situation in Somalia has made WFP operations extremely dangerous. But despite the killing, officials say the WFP food aboard the trucks was not looted.