Only a trickle of aid managed on Monday to reach the desperately hungry people of the northern Gaza Strip, where the UN has warned that hundreds of thousands of Palestinians face a growing threat of famine after nearly five months of fighting and blockade.

Fifteen trucks were dispatched overnight to northern Gaza as part of a relief effort involving Palestinian businesspeople, according to COGAT, the Israeli military body that regulates aid to the Palestinians. But at least five of those were looted along the way, according to an Israeli official who was not authorized to comment publicly, and so spoke on condition of anonymity.

It was unclear exactly how many of the trucks reached their intended destination, Gaza City’s Zeitoun neighborhood. Izzat Aqel, a Palestinian businessperson involved in the operation, said he aimed to send another 30 trucks with food relief to northern Gaza on Monday night.

Aid officials have warned that Palestinians in Gaza could be on the brink of famine unless relief is substantially stepped up, with over 500,000 people already facing a dire lack of food.