Hazem Isleem, a Palestinian truck driver, was passing through the ruins of the southern Gaza Strip last month with a truckload of aid when armed looters ambushed his convoy.

One of the gunmen broke into his truck, forcing him to drive to a nearby field and unload thousands of pounds of flour intended for hungry Palestinians, he said by phone from Gaza. By the next morning, the gang had stripped virtually all of the supplies from the convoy of about 100 trucks of United Nations aid, enough to feed tens of thousands of people, in what the United Nations described as one of the worst such episodes of the war.

“It was terrifying,” said Isleem, 47, whom the looters held for 13 hours while they pillaged the flour. “But the worst part was we weren’t able to deliver the food to the people.”

Israel’s bombardment and invasion of Gaza in response to the Hamas-led Oct. 7 attack last year has unleashed a humanitarian crisis in the enclave, with more than 45,000 people dead, according to local health officials, who do not distinguish between civilians and combatants. Hunger is widespread, and Israel has placed restrictions on the entry of aid into Gaza and blocked movement of aid trucks between the north and south.

Though Hamas has been routed in much of the territory, Israel has not put an alternative government in place. In parts of southern Gaza, armed gangs have filled the resulting power vacuum, leaving aid groups unwilling to risk delivering supplies.

The U.N. agency for Palestinian refugees, UNRWA, said this month that it would no longer deliver aid through Kerem Shalom, the main border crossing between Israel and southern Gaza, because of the breakdown in law and order.

Hundreds of truckloads of relief are piling up at the crossing in part because aid groups fear they will be looted.

What began as smaller-scale attempts to seize aid early in the year — often by hungry residents of Gaza — has now become “systematic, tactical, armed, crime-syndicate looting” by organized groups, said Georgios Petropoulos, a senior U.N. official based in the southern city of Rafah. “This is just larceny writ large,” he said.

This article is based on more than 20 interviews with Israeli and U.N. officials, aid workers, Gaza residents and Palestinian businesspeople. The New York Times also reviewed internal U.N. memos in which officials discussed the looting and its consequences.

The situation in Gaza deteriorated after the Israeli military invaded Rafah in May, seeking to oust Hamas from one of its final strongholds. Hamas’ security forces fled, and organized gangs — with no one stopping them — began intercepting aid trucks as they headed from the main border crossing into southern Gaza. They are stealing flour, oil and other commodities and selling them at astronomical prices, aid groups and residents say.

In southern Gaza, the price of a 55-pound sack of flour has risen to as much as $220. In northern Gaza, where there are fewer aid disruptions, the same sack can cost as little as $10.

International aid workers have accused Israel of ignoring the problem and allowing looters to act with impunity. The United Nations does not allow Israeli soldiers to protect aid convoys, fearing that would compromise its neutrality, and its officials have called on Israel to allow the Gaza police, which are under Hamas’ authority, to secure the convoys.

Israel, which seeks to uproot Hamas, accuses the group of stealing international aid and says that the police are just another arm of the militant group. They have repeatedly targeted Hamas’ police force, severely weakening it, and police officers are rarely seen in much of Gaza, residents say.

Over the past two weeks, Israel has allowed some aid trucks to travel along Gaza’s border with Egypt, a new route fully controlled by the Israeli military. U.N. agencies have been able to avoid looters and deliver some relief.

But that has not done enough to address the shortfall in aid, humanitarian groups and residents say. The high prices of goods sold by looters have contributed to desperate scenes among ordinary Gaza residents fighting for what little affordable food is available.

In late November, crowds had already gathered at Zadna bakery in the central city of Deir al Balah hours before it opened, hoping to buy a 20-piece bag of bread for the U.N.-subsidized price of $1. Suddenly, mayhem broke loose as ordinary people in the crowd — some brandishing knives — pushed to reach the front of the line, said Abdelhalim Awad, the bakery’s owner.

During the commotion, gunshots rang out. Two women were killed and others were injured, he said, and a third later died of her wounds.

With unrest rising, all of the U.N.-backed bakeries in southern and central Gaza have closed their doors for now.

“Today, the ordinary Gazan’s dream, his aspiration, is to obtain a piece of bread,” Awad said. “I can’t say anything sadder than that.”

Transportation company owners in Gaza, truck drivers and aid groups say multiple gangs have participated in looting recently. But many people involved in aid delivery named Yasser Abu Shabab, 35, as the man who runs the most sophisticated operation.

They say Abu Shabab’s gang dominates much of the Nasr neighborhood in eastern Rafah, which the war has transformed into a wasteland. Petropoulos called him “the self-styled power broker of east Rafah.”

Isleem said the looters who captured him in Rafah told him Abu Shabab was their boss. Awad Abid, a displaced Gaza resident who said he had tried to buy flour from Abu Shabab’s gang in Rafah, said he had seen gunmen guarding warehouses containing stolen cartons of U.N.-marked aid.

“I asked one of them for a sack of flour to feed my children,” Abid said, “and he raised a pistol at me.”

Abu Shabab denied looting aid trucks on a large scale, although he conceded that his men — armed with Kalashnikov assault rifles — had raided half a dozen or so since the start of the war.

“We are taking trucks so we can eat, not so we can sell,” he said in a phone interview, claiming he was feeding his family and neighbors. “Every hungry person is taking aid.” He accused Hamas of being primarily responsible for stealing the aid, a claim Hamas has denied.

The looters’ chokehold on supplies and the soaring prices are undermining Hamas in the areas it still controls. On Nov. 25, Hamas’ security forces raided Abu Shabab’s neighborhood, killing more than 20 people, including his brother, Abu Shabab said.

Official Hamas media reported at the time that its forces had killed 20 members of “gangs of thieves who were stealing aid.”

As looters have run rampant in areas nominally controlled by the Israeli military, truck drivers and aid workers have suggested the Israeli military mostly turns a blind eye.

“There is continued tolerance by the Israel Defense Forces of unacceptable amounts of looting of areas that are ostensibly and de facto under their military control,” Petropoulos said.

At times, Israeli tanks have deployed along main roads where aid trucks travel. And Israeli ministers have said they debated authorizing private security contractors to protect international aid convoys inside Gaza.

Until recently, Israeli forces largely did not target the looters unless they were affiliated with Hamas or other militant groups, according to U.N. officials. But that appears to have changed in recent weeks.

In Israeli military drone footage viewed by the Times, looters can be seen confiscating white sacks of aid from cars in southern Gaza in November. Minutes later, an Israeli airstrike killed them, the footage appears to show.

Shani Sasson, a spokesperson for the Israeli military agency that regulates aid to Gaza, said Israeli forces were targeting armed looters who attacked convoys, not just those affiliated with Hamas. She denied that Israel was providing any immunity to criminal gangs stealing aid.

In late November, Israeli forces opened fire on looters waiting to waylay trucks in Rafah, forcing them to retreat, according to an internal U.N. memo. With the path cleared, U.N. aid trucks rushed toward central Gaza.

But the gangs were far from deterred.

The looters soon regrouped and hijacked them on the road, the U.N. memo said. The trucks were stripped bare.

The New York Times News Service