Hundreds of people lined up at the Costco in Hawthorne on Friday to stock up on items such as water and toilet paper.
More than 100 people were lined up outside the store waiting to get in. Once inside there were similar lines waiting to get water.
"It was actually pretty crazy today. I've never seen anything like it at Costco," said Sami Saheb of Redondo Beach, who was buying water and bath tissue.
"A huge line to go inside, then another line on the inside. Usually where the water is you just go right in. But there was a long line leading all the way almost to the cash registers, just to get to the water."
Dan Watson of Hermosa Beach showed up at the store just to buy a few items for his weekend lunch. His wife jokingly warned him before he showed up to expect people preparing for "the zombie apocalypse."
Still, he said, since he didn't need to buy water or cleaning supplies, he was able to avoid the big lines and get in and out of the store in about 10 minutes.
He said the tone of people waiting was mostly polite, with no fighting or obvious rush.
There was one disappointment though: "I was hoping to get some samples while I was here. I was told no more samples at Costco due to the panic as well."
Other stores are reporting shortages of cleaning items, such as hand wipes and sanitizer.
Adam Kline, owner of Delta Distributing in Arcadia, points to empty spots on his shelves that used to hold products such as sanitizing wipes.
"It used to be here. There's nothing left now," he said.
Kline's business sells janitorial supplies to cleaning companies. He says he hasn't been this busy since the SARS outbreak in the early 2000s.
Some of the shortages mystify him.
"I certainly hear a lot of my clients saying what's with the water, what's with the toilet paper? I don't get that either."
Online shoppers are reporting steep markups on some items.
On Amazon, some sellers were offering a two-pack of Purell for $84.99 and face masks at a markup of 582%.
State officials are warning about price gouging, saying it is illegal to raise prices more than 10% during a declared state emergency.
State Attorney General Xavier Becerra says violation of price-gouging laws can be punished with up to one year in prison and/or a fine up to $10,000.