<span>Photograph: Ricardo B Brazziell/AP</span>

Photograph: Ricardo B Brazziell/AP

Food banks in Texas have gone into disaster mode as they ramp up operations to tackle a surge in hunger after unprecedented freezing conditions disrupted almost every part of the food supply chain in the state.

Grocery stores are empty, school meal programs suspended, and deliveries disrupted by untreated treacherous roads that have left millions of Texans trapped in precarious living conditions with dwindling food supplies.

Even those who did stockpile before the Arctic conditions swept in have lost refrigerated groceries due to lengthy power cuts and cannot cook what food they do have without electricity or gas.

Related: Millions of Texans struggle for drinking water following deadly winter storm

In the worst-affected areas, food banks and pantries were forced to close for several days this week as it was impossible for staff and vehicles to get to the distribution sites. Relief was limited to disaster boxes sent to people seeking refuge in warming shelters.

On Thursday, the disruption to energy and safe water supplies had food banks scrambling to procure large quantities of bottled water and ready meals and snacks that do not require cooking.

“This is a disaster. We are doing rapid needs assessments so we can get appropriate food to those people quickly. When everything thaws, we’re preparing for a massive spike in demand,” said Valerie Hawthorne, director of government relations at the North Texas Food Bank, based in Dallas. “This has been the longest week of all our lives.”

A woman carries bottled water she received from a warming center and shelter in Galveston.

A woman carries bottled water she received from a warming center and shelter in Galveston. Photograph: Adrees Latif/Reuters

Before the big freeze, this food bank ran two drive-through food distribution sites every day, serving between 300 and 1,500 families at each pop-up location. This week they were all were cancelled, though one is planned for Saturday, leaving thousands of families without enough food or reliant on relatives, neighbors, and mutual aid groups.

In addition to the regulars, advocates expect a rise in low-paid service industry workers – who are often just one or two paychecks away from hunger and will not be paid this week as many restaurants and bars were forced to close.

Hunger was a serious problem in Texas even before the pandemic and the latest weather disaster, with about 4.3 million Texans struggling with hunger in 2019, including one in every five children.

Covid triggered an economic crisis that led to a demand for food aid doubling in many parts of Texas amid record unemployment and underemployment levels.

The extraordinary freeze has once again exposed existing deep inequalities that will make it much harder for low-income households to recover, according to Brian Greene, CEO of the Houston Food Bank. “The aftermath of every disaster is much harder on low-income families, who are going to be in more trouble even after the power and water comes back on,” he said.

Almost two-fifths of Americans do not have enough cash or savings to cope with an unexpected $400 expense such as burst pipes or a collapsed roof, according to research by the Federal Reserve,

Empty shelves are seen at a store in Austin.

Empty shelves are seen at a store in Austin. Photograph: Kolby Lee/Reuters

In rural Brazoria county, south of Houston, the pantry reopened on Thursday and served 140 families in just two hours – compared with 170 families usually seen over the course of an ordinary week. About 75% were first-timers desperate for food and water and were given enough for three days, as that’s all the pantry had available.

“It’s crazy. People are out of options. They’ve gone into survival mode to get what they can,” said Terri Willis, executive director of the Brazoria County Dream Center, which operates the pantry. “We are all in disaster mode.”

Long lines extend outside grocery stores with empty shelves, and water supplies have been disrupted by boil advisories and burst pipes; electricity is needed for those in rural areas with private wells.

Willis is particularly concerned about the district’s vulnerable children, as her organization usually provides a backpack of weekend meals for 620 kids who would otherwise go hungry. The schools are closed, so those children will go without. “It’s heart-wrenching. I’ve been one of those kids who goes hungry over the weekend. I’m praying that their parents can get here,” Willis said.

In Dallas, youngsters are also a huge concern: citywide, 87% of school children live in low-income households. Thousands depend on free school meals, with some receiving four meals a day – breakfast, lunch, a snack and dinner – but many schools were unable to offer any this week due to power cuts, burst pipes, water advisories and shortages.

Related: The Texans facing blackouts and burst pipes: ‘Do I wait for the ceiling to cave in?’

Advocates are also worried about the city’s senior residents who rely on food aid to get enough to eat and may have been cut off from all services for several days. “It’s the elderly that have kept most of us up this week. They truly are the most vulnerable population, and we just don’t know how many have been unable to ask for help,” said Hawthorne.

At the other end of the food chain, fruit and vegetable crops in the Rio Grande Valley have been ruined by the extreme cold, while dairy farmers across the state are pouring millions of dollars of milk down the drain because they cannot get it to dairies. The drop in production could have short- and medium-term consequences on availability and prices.

Scientists have long warned that global heating is causing extreme weather events to become more frequent and intense – and to strike in places unaccustomed to and ill-equipped to deal with extreme heat or freezing temperatures.

The disruption to food supplies in Texas shows how poorly prepared the US is to deal with the climate crisis, according to Molly Anderson, director of the food studies program at Middlebury College in Vermont.

“What we see in Texas demonstrates a lack of planning for resilience and a failure to recognize that climate weirding is here and that it’s already impacting the food chain,” she said.