DEIR AL-BALAH, Gaza Strip >> A new aid system in Gaza opened its first distribution hubs Monday, according to a U.S.-backed group that said it began delivering food to Palestinians who face growing hunger after Israel’s nearly three-month blockade to pressure Hamas.

The Gaza Humanitarian Foundation is taking over the handling of aid despite objections from United Nations. The desperately needed supplies started flowing on a day that saw Israeli strikes kill at least 52 people in Gaza.

The group said truckloads of food — it did not say how many — had been delivered to its hubs, and distribution to Palestinians had begun.

“More trucks with aid will be delivered tomorrow, with the flow of aid increasing each day,” it said in a statement.

The U.N. and aid groups have pushed back against the new system, backed by Israel and the United States. They assert that Israel is trying to use food as a weapon and say a new system won’t be effective.

Israel has pushed for an alternative aid delivery plan because it says it must stop Hamas from seizing aid. The U.N. has denied that the militant group has diverted large amounts.

The foundation began operations a day after the resignation of its executive director. Jake Wood, an American, said it had become clear the foundation would not be allowed to operate independently. It’s not clear who is funding the group.

The organization is made up of former humanitarian, government and military officials. It has said its distribution points will be guarded by private security firms and that the aid would reach a million Palestinians — around half of Gaza’s population — by the end of the week.

Under pressure from allies, Israel began allowing a trickle of humanitarian aid into Gaza last week after blocking all food, medicine, fuel or other goods from entering since early March. Aid groups have warned of famine and say the aid that has come in is nowhere near enough to meeting mounting needs.

Hamas warned Palestinians on Monday not to cooperate with the new aid system, saying it is aimed at furthering those objectives.

The Israeli airstrikes killed at least 36 people in a school-turned-shelter that was hit as people slept, setting their belongings ablaze, according to local health officials. The military said it targeted militants operating from the school.

Israel renewed its offensive in March after ending a ceasefire with Hamas.