When dozens of desperate people began showing up at its warehouse — which is not a food distribution center — the Alameda County Community Food Bank realized that the coronavirus pandemic and widespread layoffs were causing a hunger crisis.

“It was a telling moment when we realized we needed to readjust in real time,” said Mike Altfest, director of community engagement and marketing. “We are seeing an unprecedented surge in demand.”

The agency scrambled to open up a new drive-through distribution center nearby where families could drive up, pop their trunks and have groceries loaded inside. It started March 30 serving about 30 households. Within 10 days, that was up to 470 households with cars weaving around a huge parking lot. On Friday, a staggering 743 cars showed up.

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Throughout the Bay Area, food banks — nonprofits that distribute free groceries to those in need, often via social service agencies — tell similar stories of being inundated with urgent requests from people who’ve lost their incomes during the shutdown that has left at least 2.4 million Californians newly unemployed. The vast majority of job loss occurred among lower-income people — hotel housekeepers, cooks, waiters, janitors, cabbies, health aides, day care workers and others who often live paycheck to paycheck.

“It gives you chills thinking about how deep the hunger is now,” said Andrew Cheyne, director of government affairs for the California Association of Food Banks.

Many in the current surge had not previously sought help to keep food on their tables.

“We’ve seen the emergence of a new population that has never before relied on food banks,” said Cassidie Carmen Bates, policy and advocacy manager for the Food Bank of Contra Costa & Solano. “Circumstances have made it impossible for many people to provide the food their family needs.”

The Redwood Empire Food Bank, which serves five counties from Sonoma to the Oregon border, is hearing from many people who “don’t even know what a food bank is,” said Lisa Cannon, director of development. “They just heard that they can come here for food.”

What prompted them to call? The answer is simple.

“Job loss,” she said. “Lots of job loss.”

Food banks are responding by adding new pop-up pantries; creating drive-through sites; boxing up food so it can be handed out while maintaining the distance under health orders; assembling emergency kits of staples; extending their distribution hours; and roping in the National Guard for assistance in their warehouses. But money, food and volunteers are all in short supply, exacerbating the crunch.

“I’ve been doing this work for more than 20 years and I’ve never seen anything like this,” said Leslie Bacho, CEO of Second Harvest of Silicon Valley Food Bank, which serves San Mateo and Santa Clara counties. “Our hotline used to handle about 180 calls a day; now there are 1,200 a day from people who are recently unemployed and are so worried. There is so much anxiety right now.”

A Second Harvest partner’s drive-through distribution center at a nearby church is now serving 1,200 households a day, up from 400 before the crisis. So many cars came for the Wednesday and Thursday food giveaways that the police had to intervene because they were blocking traffic, she said. The site hopes to add a neighboring parking lot to ease the jam.

Food banks often distribute groceries through community groups such as youth clubs, churches, synagogues or senior centers. Many of those food pantries had to close because their locations were shuttered, they needed to observe social distancing, volunteers were cloistered at home, or they deal with vulnerable populations such as seniors.

That’s led to some creative new strategies. Almost every food bank is setting up new distribution sites, sometimes tag-teaming with the daily free meal distributions for low-income students offered at many schools.

The San Francisco-Marin Food Bank created a program called Pantry at Home to deliver directly to 7,000 homebound seniors who used to visit its pantries for groceries.

“Our goal is to get to 12,000,” said Katy McKnight, director of community engagement. “It’s inspiring to see how quickly we got nimble to adapt our operations to serve our community.”

Food banks are adapting in other ways too. They’re mindful of social distancing, both in their warehouses and when distributing food.

Rather than letting clients “shop” for groceries, the banks now preassemble separate boxes of produce, shelf-stable items and refrigerated food that can be handed out more simply.

Drive-through distributions to minimize direct contact have also become common throughout Bay Area food distribution sites — even though that can lead to blocks-long queues of cars.

Cities are stepping up, too. San Francisco on Monday said it will lend city employees to food banks and create a resource page on a city website about food access for its residents.

Food banks and their pantry partners distribute food without asking many questions, other than a few basics such as ZIP code and household size. They don’t ask about immigration status, for instance. The food banks also help clients sign up with CalFresh, the state’s version of food stamps, which requires more paperwork but has loosened many requirements for the moment as it faces a historic spike in applications.

It’s not just food that cash-strapped people need.

SupplyBank.org acts like a food bank for non-edible necessities — diapers, tampons and sanitary pads, and school supplies, for instance — which it provides to community groups statewide to distribute.

“We’ve never been as busy as we are today,” said Benito Delgado-Olson, executive director.

The Oakland organization has increased distribution of school supplies for students now studying at home, as well as diapers and wipes, which are expensive and not something families can forgo. It’s seeing much more demand for liquid soap, disinfectant wipes and cleaning supplies. And, of course, toilet paper, which panic shoppers have snatched from store shelves nationwide.

“Until two months ago, toilet paper was something everybody could get fairly easily” so SupplyBank didn’t provide it, Delgado-Olson said. But now, with that essential commodity often sold out, he feels lucky to have found two manufacturers who can supply it directly.

All food banks acknowledge that the current situation is likely to last for months if not longer.

“For the populations we serve, people who are most vulnerable, it’s not like shelter in place will end and everybody will just bounce back,” said Second Harvest’s Bacho. “We serve folks who don’t have a lot of cushion. It will take longer for families to recover from this economic hardship.”

Carolyn Said is a San Francisco Chronicle staff writer. Email: csaid@sfchronicle.com Twitter: @csaid

Bay Area food banks Food banks help anyone in need, asking only a few basic questions about ZIP code and household size. They prefer that new clients call their hotlines or visit their websites for initial intake and find the best distribution site for them. Alameda County Community Food Bank www.accfb.org Community Action of Napa Valley Food Bank www.canv.org Food Bank of Contra Costa & Solano www.foodbankccs.org Redwood Empire Food Bank www.refb.org San Francisco-Marin Food Bank www.sfmfoodbank.org Second Harvest of Silicon Valley www.shfb.org