The ongoing blockade of Gaza has pushed the enclave’s 2.3 million people to the brink of starvation, Cindy McCain, executive director of the U.N.’s World Food Program, warned on Sunday.

Israel has besieged the densely populated coastal region for almost two weeks, refusing to allow in food and medical aid amid fears it could fall into the hands of the militant group Hamas. As Israel intensified airstrikes over the weekend in preparation for a ground invasion, the first 20 aid trucks entered Gaza on Saturday after being blocked near the Egyptian-controlled Rafah border crossing.

But a lot more aid needs to be delivered, McCain told POLITICO.

“Right now we’re facing a catastrophe in the area with the inability to feed people and the inability for the people to find anything to eat at all,” McCain said in an interview Sunday. “These people are going to starve to death unless we can get in.”

The Gaza Strip has been besieged by Israeli forces since October 9, when Israel’s Defense Minister Yoav Gallan moved to restrict all access to food, water and energy in the enclave in retaliation for a surprise incursion from the Hamas militant group that killed at least 1,400 people in Israel.

Israel’s retaliatory air and missile strikes have killed at least 4,385 Palestinians, including hundreds of children, and displaced more than a million people, Gaza’s health ministry said on Saturday.

Israel intensified its airstrikes Saturday night, killing more than 50 Palestinians, according to medical authorities in Gaza. The Israeli military warned that civilians who refused to relocate to the southern part of Gaza could be identified as sympathizers with a terrorist organization, Reuters reported.

“We can’t allow politics to begin to shape how humanitarian aid is given or sent in and so that’s what we’re pressing on people,” McCain said, noting the increased risk of diseases like cholera due to the collapse of Gaza’s water and sanitation services. “This is a humanitarian crisis. We need to be in there and we need to be in there now.”

Before the blockade, about 400 aid trucks entered the territory every day. After a visit by U.S. President Joe Biden last week, Israel said it would allow deliveries of food, water and medicine — but not fuel — from Egypt, provided they were limited to civilians in the southern part of Gaza and did not go to Hamas militants.

The 20 aid trucks that entered on Saturday “are not enough,” Samer AbdelJaber, the World Food Program’s country director for Palestine, said in a statement.

Saturday’s deliveries “are a window of hope amid a catastrophic situation,” AbdelJaber said. “But they are not enough. We need continuous access. People need food, water and medicine every day, not just once.”

McCain said the WFP had systems in place to minimize the risk. “We have ways to be able to track and trace our goods,” she said. “We also have ways to make sure that our recipients are actually the people who should be getting it and not the bad guys.”