Gazans stormed a warehouse of the United Nations Palestinian refugee agency (UNRWA) in Khan Younis, grabbing flour and "basic survival items" on Saturday (28 October) the organisation said.
Aid supplies to the area have been choked since Israel began bombarding the enclave after Hamas' attack on Israel on 7 October.
Air strikes in Palestine have completely stretched UNRWA's ability to help people in Gaza, the organisation added.
UNRWA provides public services including schools, primary healthcare and humanitarian aid in Gaza, the West Bank, Jordan, Syria and Lebanon.