It appears growing concerns about coronavirus have led to more empty shelves at Costcos and Walmarts around the country.
Just last week, the Centers for Disease Control and Prevention told Congress there is no need for healthy Americans to stock up on supplies.
But that's not stopping some shoppers from worrying.
People are stockpiling everything from water and toilet paper to hand sanitizer and face masks. The global run on sales of masks come as medical experts' advice that most people who aren't sick don't need to wear them.
"I feel the pressure. I feel like something big is coming," shopper Lubia Calderon said.
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Officials are concerned about a run on masks, because it could limit their availability to health care professionals.
Walgreens, Home Depot, Lowe's and True Value Hardware are reporting a sharp uptick in sales of masks over the past several weeks and say they are scrambling to get more from suppliers.
Home Depot, the nation's largest home improvement chain, has limited sales of N95 respirators to 10 per person. They have a close facial fit and more filtration material than general surgical masks, enabling them to keep out at least 95% of particles.
The global coronavirus spread continued Sunday, with 76 reported cases in the United States. There are now more than 80,000 cases worldwide and nearly 3,000 deaths globally.
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How to Wash Your Hands
The Associated Press contributed to this report.