Gun stores across the Bay Area did brisk business Tuesday, selling firearms and ammunition to customers rattled by the coronavirus pandemic and staying open in apparent defiance of the “shelter-in-place” order intended to slow the spread of disease.

Firearms dealers from Novato to Sunnyvale reported a spike in sales, and buyers in multiple cities waited in long lines that spilled out doors and into parking lots.

More than two-dozen people — mostly men — lined up outside the City Arms gun store in Pacifica. No other business in the Eureka Square shopping center was open during the mandated “shelter in place” hovering over San Mateo County and five other Bay Area counties. Not the yoga studio next door or the dance and exercise studios a few doors down.

But the beefy man in the blue-and-white “City Arms” polo shirt who stepped outside to see a reporter and photographer approach his store wasn’t about to answer questions about why his place was open.

“Please leave,” the man said. “This is private property.”

He might have called the police — or he might not have — depending on whether a gun store can legitimately be called an essential service.

Either way, the people in line seemed glad that City Arms was open.

“The government is trying to do everything it can to keep society intact. But if society is unraveling, it’s up to us to protect ourselves,” said Andrew Dominguez, 36, a real estate agent in Pacifica who waited near the end of the slow-moving line to buy ammo for his shotgun.

John Chen, 40, agreed. He lives in Oakland but has construction outlets around the Bay Area, including in Pacifica. He was at City Arms to buy his first pistol for personal defense.

“This virus gave me the motivation,” Chen said. “I’ve always wanted to have a gun, but I’ve been lazy. I see the news now, and the outbreak and the chaos.”

Chen said crime is on the rise, although stories across the country show that homicides and certain other crimes are way down. But Chen saw a video of a cruel beating and robbery in San Francisco’s Chinatown in November, and said he believes otherwise.

“I don’t like guns,” he said. “But crime is getting worse.”

Jackson Lu, 24, came bounding out of the gun store, carrying a new $500 Glock 19 in its black plastic case. He wasn’t about to open it to show it off, though.

“I feel like there’s a lot of crazy stuff happening around the world,” he said. “I want to feel safe.”

At Marin Firearms in Novato, four men and one woman stood in line outside the entrance at 1:30 p.m. as a FedEx truck delivered fresh merchandise. The driver pushed a cart piled with about 20 cardboard boxes, some of them long and thin, the right size for rifles or shotguns, into the store.

Inside, a young man working the counter explained that business started picking up about a week ago. He was limiting the number of customers inside the store to three at a time, he said, and in coming weeks, the store would stay open to serve the firearms community “until I drop dead.” He said he didn’t want to give his name because only the owner spoke to the press and the owner wasn’t there.

Asked if the store was supposed to be open at all, given that only essential businesses are exempt from the lockdown, the Marin Firearms employee said, “As far as I know, we’re essential. No one’s told us we’re not.”

Outside, Sharon Femenia, 49, waited to buy ammo for her family’s handguns and rifles.

“Just decided we needed to stock up a little bit,” said Sharon, a Novato resident and gun collector.

“Mainly for home defense,” said her son, Peter, who held their dog, Stig, a Siberian Husky, on a leash. “Because we don’t know how much longer we’ll be on lockdown.”

“It’s kind of eerie,” Sharon said, referring to the recent wave of panic-buying that has emptied the shelves of groceries and drugstores.

Reached on the phone in the early afternoon and asked if his store was seeing a high volume of sales, Gabriel Vaughn, owner of Sportsman’s in Petaluma, started laughing.

“God bless you,” he said. “Yeah, that’s an understatement.”

His store is in Sonoma County, which has not issued a shelter-in-place order. Vaughn said that 40 people were standing in line as he was speaking and that Monday was the single busiest day in the store’s history. People are panic-buying guns for the “same reasons that grocery stores are sold out,” Vaughn said. “Once anybody sees that people are willing to commit violence over toilet paper, a nonessential (item), then people start thinking worst-case scenario.”

He added that about 90% of his customers in recent days have been first-time gun buyers.

John Parkin, owner of Coyote Point Armory in Burlingame, said the city shut down his shop Tuesday morning. But a half hour later, after discussing the situation with Burlingame police, Parkin said he was allowed to open.

“We are essential for providing tools for the safety in your home,” Parkin said. “In times like this, people need security in their homes.”

He said Burlingame police were going to check with San Mateo County officials for guidance.

He’s already worried that customers waiting for the mandatory 10-day waiting period to pick up firearms will have their background checks delayed due to the shutdown.

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“People are being denied their Second Amendment right,” Parkin said.

Yet his business was booming, thanks to coronavirus fears. Parkin estimated business surged 500% in two weeks.

“It’s been absolutely off the charts. I’m completely out of hand guns. I’m just preselling stuff,” he said.

“It’s obvious people feel very insecure with what the government is doing” he said. “And people feel they need to protect their home if things get strange with the coronavirus.”

Parkin took social-distancing steps at his store, allowing only three people in at once, while others had to line up outside.

An employee from U.S. Firearms Co. on South Mary Avenue in Sunnyvale, who asked not to be identified, said his shop is closed under the county’s shelter-in-place policy. But the store saw a “huge uptick” in clientele at the end of February.

People are afraid, he said. “They’re afraid that (the coronavirus) is going to cause uncertain times and they’re afraid they’re going to have to defend themselves.”

“A lot of people say they’ve been meaning to get protection for their safety and this has spurred them to do that,” he said, adding that most customers want their guns repaired.

In the weeks before he closing, he said, business quadrupled.

Law enforcement agencies in Novato, San Rafael and Pacifica did not respond to requests for comment about whether gun stores fall under the essential services provision of Bay Area shelter-in-place edicts

Jason Fagone, Matthias Gafni, Tatiana Sanchez and Nanette Asimov are San Francisco Chronicle staff writers. Email: jfagone@sfchronicle.com, matthias.gafni@sfchronicle.com, tatiana.sanchez@sfchronicle.com and nasimov@sfchronicle.com Twitter: @jfagone, @mgafni, @TatianaYSanchez and @NanetteAsimov