President Obama met for more than an hour with congressional leaders Wednesday evening, saying he will not negotiate as the government shutdown continues into its third day. Personnel of the CIA and FBI have been ordered to stay home, and due to short staff at the National Institutes of Health, children needing cancer treatments may not receive them.

On the third day of a government shutdown with no end in sight, families, government employees and private citizens across the country were feeling the effects of the battle in Washington. Many voiced their frustrations on Facebook, Instagram, and Twitter using the social media tag #DearCongress. With no clear indication of when lawmakers on Capitol Hill will pass a bill to fund the government, here's how some Americans have already been hit:

San Diego military families

Families that rely on military commissaries, or base shops, to keep living costs down will have to shop elsewhere after the stores shut down Wednesday. The increase in expenses could be steep for furloughed personnel on bases in cities like San Diego, where a trip to the grocery store can be pricey.

“We’re very lucky that we do have access to the commissary, especially in a city like San Diego where the cost of living is expensive,” said Catie Griffith, whose husband’s Navy pay will be hard hit by the higher shopping bills, according to NBC San Diego. And cash was already tight after Griffith left her job as a teacher to take care of the couple’s two children.

Dave Summers / NBC San Diego Empty store shelves at a base commissary on Tuesday in San Diego.

“The line was wrapping around the entire store” before the commissary shut down, Griffith told NBC San Diego.

The Defense Commissary Agency, which manages the commissaries on military bases at home and abroad, says on its website that military families save more than 30 percent on average at the stores. The site was not being updated while the shutdown went on, but the agency said in a statement online that foreign commissaries would remain open.

“We are acutely aware of the hardships placed on all our customers if we cannot deliver their commissary benefit,” agency director Joseph H. Jeu said in the statement. “However, because of their geographic location, our service members and their families overseas have a more critical dependence on commissaries, and we are prepared to continue that support.”

A fallen New Mexico firefighter’s wife

Heidi Adams, whose firefighter husband was found dead in September, delivered the couple’s daughter just weeks ago – and is now fighting to get her husband’s benefits amid the ongoing shutdown, NBC News’ affiliate KOB reported from New Mexico.

The body of U.S. Forest Service firefighter Token Adams was found in early September, the victim of an apparent ATV crash after he rode out to investigate a wildfire in the Jemez Mountains a week earlier. Heidi Adams has said she was all set to start receiving his federal benefits for herself and her children — until her meeting scheduled for Wednesday was canceled. For now, she’s getting by on donations, she told KOB.

“That’s what I’m living off of,” Adams, who is trying to move back to family in Maine, told the station. She said she’s been told it might take as long as four weeks before the benefits kick in.

“You know, you have families who are both on government pay, and you think up to four weeks without a paycheck, what’s that going to do for their families?” Adams said according to KOB. “I feel for them. It’s going to be really tough.”

The search for a missing Idaho hiker

Searchers braved rough terrain on Wednesday at Idaho’s Craters of the Moon National Monument after fears that the shutdown would bring a halt to their hunt for signs of hiker Dr. Jo Elliott-Blakeslee, who set out on Sept. 19. Her partner was found dead a week later, likely of dehydration and hypothermia, officials have said.

Dan Buckley A closed sign blocks the entrance of the Craters of the Moon National Monument and Preserve in Southern Idaho on Oct. 1 because of the government shutdown.

“After last weekend’s big effort to locate Dr. Jo, we had intended to scale back search operations given the environmental conditions we have been experiencing,” Park Superintendent Dan Buckley said in a release on Wednesday. “The probability of finding her alive has diminished, but we are committed to continuing the search until we find Dr. Jo and bring closure to her family, friends and all those who have been involved in this search.”

Elliott-Blakeslee’s family issued a desperate appeal for volunteers Tuesday, local paper the Idaho Statesman reported.

Ten of the park's 16 employees set to be furloughed were allowed to stay on as “excepted” in order to continue the hunt, the park said in a release Wednesday.

The employees “working the search are experienced rangers, in top physical condition,” park spokesman Ted Stout said in the release. “The terrain in the park can be brutal; it, along with the adverse weather conditions we have been experiencing, it has has already taken a toll on searchers and search dogs who have been working to locate our missing subject.”

A Boston food pantry

An American Red Cross food pantry that’s already a last resort for many hungry people feared a strain on its stores as demand increases and funds dry up as a result of the government shutdown. The food pantry in the Boston neighborhood of Roxbury is supported by a mix of private donations and federal funds.

So as the government money disappears with no end to the shutdown in sight, Red Cross officials with the food bank are concerned about their ability to provide meals for some of the city’s neediest, NBC partner New England Cable News reported.

“For many people we are the only source of fresh vegetables and other perishable foods in their diet. About 80 percent of the food we give out here is fresh,” Jarrett Barrios, the CEO of Red Cross of Eastern Massachusetts, told NECN. “And if we don’t keep getting that in, we will not be able to keep giving it out.”

“In general, when we see these difficult economic circumstances, we see a spike in our food pantry usage because people aren’t sure,” Barrios told NECN.

J'Kai Jackson of Atlanta talks about the possible impact on her and her daughter Savannah now that the government has stopped funding WIC.

There had already been about a 10 percent increase in the number of people using the food bank over last year, Barrios said. The pantry will usually give about 44 pounds of emergency food to a family, but if demand increases and the shutdown runs on indefinitely, the Red Cross may have to adjust.

“Demand is going to go up. We are not going to turn anybody away. But it might mean, what we normally give people, we might have to give a little bit less,” Barrios said, according to NECN.

Cancer-stricken children

A small but desperate group of children with hard-to-cure cancer could have their treatment delayed at the National Institutes of Health Clinical Center as a result of the government shutdown, officials said.

About 200 people a week, including some 30 children — many with cancer — are being told their enrollment in the center’s clinical trials will have to wait until federal agencies reopen for business, NIH Director Dr. Francis Collins told the Wall Street Journal.

For those families already grappling with anxiety and fear, any delay is too long, said Dr. Peter Adamson, a pediatric cancer expert at The Children’s Hospital of Philadelphia.

Slideshow: Government shutdown Win Mcnamee / Getty Images The impact of the first government shutdown in 17 years was felt across America as offices were shuttered and workers were sent home after lawmakers failed to come to a deal. Launch slideshow

“One thing they don’t have is time,” he said. “Even a delay of a week is too much.”

Still, despite some news reports about the effect on cancer trials, the delays won’t be widespread, Adamson said. Kids in the most dire situations can still be accepted for treatment because exceptions can be made for medically necessary cases, according to a Health and Human Services contingency plan.

And existing patients will still be treated, despite furloughs that affected nearly three-quarters of NIH staff — roughly 14,000 of nearly 19,000 employees.

“It’s difficult to make the leap that we’re risking lives,” Adamson said. “But we’re absolutely impacting families facing unimaginable situations.”

If the delay continues for a short time – a few days or a week – the impact will be minimal, said Adamson, whose research includes dozens of clinical trials covering every aspect of cancer diagnosis and treatment.

But if it stretches out longer — months or more — the effect on research could be profound, especially combined with the ongoing impact of sequestration, the automatic government spending cuts that trimmed 5 percent of the NIH budget, or $1.55 billion.

“This impact will pale in comparison to sequestration,” Adamson said.

Anger and frustration mounts as the government shutdown continues. With federal employees on furlough and government programs on hold, the impact is spreading across America. NBC's John Yang reports.

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