Israel bombarded Gaza again on Thursday and local health officials said more than 60 people had been killed in the attacks over the past day, as hungry Palestinians scrambled for food handouts under a new Israeli-backed aid operation that has been heavily criticized.

The United Nations says the new aid system, known as the Gaza Humanitarian Foundation, is insufficient to meet basic needs for survival. In a reflection of the chaotic atmosphere surrounding distribution and the desperation of much of the population in Gaza, a large crowd of hungry people broke into a warehouse run by the U.N.’s World Food Program on Wednesday in search of food.

Images from the scene showed large crowds of Palestinians converging on the warehouse and removing sacks of looted flour. The W.F.P. said in a statement that initial reports indicated that two people had been killed and several others were injured.

While hundreds of distribution points existed under the previous aid-distribution system run by the United Nations, the new initiative requires Gaza residents to pick up aid packages from the three distribution hubs that it has operating in southern and central Gaza.

Some U.N. trucks are still making their way through a single border crossing into the enclave. But U.N. officials say that distribution to warehouses and bakeries inside Gaza has been hampered by the lack of secure routes, and that negligible quantities of food are reaching the people who need it.