Last week the American fashion industry went dark as stores and factories closed, both voluntarily and by government decree, to help prevent the spread of the new coronavirus.

Yet by this weekend, lights had flicked on again on both coasts as designers and manufacturers began to pivot from making dresses, jeans and bathing suits to making surgical face masks and other protective gear — even as President Trump addressed the United States, saying unspecified help would be on the way for hospitals that expect to be overwhelmed and under-resourced.

Los Angeles Apparel is making surgical masks; it will on Monday begin making hospital gowns as well. Dov Charney, the company’s founder and the former head of American Apparel, hopes his 150,000-square-foot factory can produce 300,000 masks and 50,000 gowns in a week.

Christian Siriano, the fashion designer, has reassigned his 10 seamstresses in New York. They are beginning to make masks and hope to produce a few thousand a week.

The swimwear company Karla Colletto had closed its factory in Virginia, but planned to retool and reopen it shortly to help combat the critical shortage of personal protective equipment that faces hospitals and health care workers.

Though they make a strange trio — Mr. Siriano, the former “Project Runway” star and current host who has become famous for his inclusive approach to dressing and has been championed by Michelle Obama; Mr. Charney, the embattled chief executive who was once forced to leave his post, accused of misuse of funds and of knowingly allowing sexual harassment; and a high-end bikini manufacturer — the group of companies reflects as much as anything the current confusion over the best response to the coronavirus crisis, and the way individuals are beginning to take action into their own hands.

Or headquarters, as it were.

None of the three manufacturers are making N95 respirator masks — medical grade protection recommended for medical professionals — though they are all responding to government calls for businesses to aid in combating the shortage of general medical supplies.

Mr. Charney and Mr. Siriano are each designing their own washable, reusable masks. They are not “medical grade,” though Mr. Siriano intends to make masks that meet F.D.A. standards as soon as he can acquire approved materials and patterns, and begin prototyping. Karla Colletto is planning to replicate masks made by 3M, using patterns and fabric sent from that long-established hospital supplier.

The moves follow the decision by LVMH Moët Hennessy Louis Vuitton, the European luxury giant, and L’Oreal and Coty, the beauty conglomerates, to use their facilities to produce large quantities of hand sanitizer for European hospitals. In Spain, Inditex, the parent company of Zara, is also looking into refitting its textile factories to make hospital gowns.

As an industry, fashion has been particularly affected by the mass business closings — and particularly active in offering resources to assist the fight against the coronavirus, stepping up as governments and the medical community scramble to respond to the crisis. In the same way automotive factories and upholsterers were retooled during World War II to supply the military, fashion is rethinking its manufacturing capabilities.

The Swimwear Story

“A week ago, our machines were humming along,” Karla Colletto said via phone on Saturday. During normal business times, her Vienna, Va., factory can produce 800 to 1,000 pieces of swimwear each week.

But like many other companies, as the coronavirus diagnosis count rose in the United States, the made-to-order swimwear company decided to cease production. Ten percent of its orders had already been canceled and the rest postponed, said Lisa Rovan, a co-founder of the brand, with Ms. Colletto.

Yet as their factory went dark, Ms. Colletto and Ms. Rovan were formulating a plan to bring as many of their 40 employees (including two dozen sewers) as possible back to work making masks and gowns for hospitals in need.

“Because we have our own facility, we can be flexible and switch gears quickly,” Ms. Colletto said. That means separating machines within the factory to be six feet apart to help prevent transmission between workers, following OSHA safety guidelines, and staying in communication with workers about any exposure to the virus.

This week, they’re awaiting fabric and patterns for disposable surgical procedure masks and gowns from 3M, the company that also produces N95 respirator masks. Once the protective gear is made, both Ms. Colletto and Ms. Rovan said they could not sell it directly to hospitals, so the products would go through a hospital supply distributor. The sales will help fund the factory employees’ paychecks.

The Siriano Situation

On Friday, Gov. Andrew Cuomo of New York issued an appeal during his daily news conference for businesses to “get creative” and manufacture protective equipment. In response Mr. Siriano tweeted: “If @NYGovCuomo says we need masks my team will help make some. I have a full sewing team still on staff working from home that can help.” (Governor Cuomo responded with a request to “follow back and we will DM you.”)

Mr. Siriano said he had been wondering how to help his employees, who were at home, and the chance to make masks was both a way to keep them occupied and to give purpose to their work.

Since then, Mr. Siriano has been in daily touch with the governor’s office, he said, as they work out how the masks should be made. He has 10 seamstresses who are working from home and are available to make the masks, which are intended both for hospital support staff and private individuals.

Mr. Siriano has continued to provide updates on Twitter; he said he was making “a few versions” to “help as many people as we can” and “get a perfect fit.” On Friday, he posted that “prototypes are happening.” The masks, which were made from a poly-lycra-cotton blend fabric that the company already had in the stockroom, are being tested according to regulations from the governor’s office.

“They have to be white, so they can be bleached,” Mr. Siriano said on a call from Connecticut, noting that they also had to withstand multiple washings.

He hopes to begin actually manufacturing the nonmedical grade masks by Monday, and projects he can produce 1,000 by the end of the week. He is also hoping to get a special exemption to reopen his office to make the masks, after sanitizing it and complying with official regulations, and is aiming to create medical-grade masks in the future.

Though the masks would initially be offered free of charge during the crisis, at a certain point, Mr. Siriano said, if demand kept rising, they “can’t afford to keep going forever” since the rest of his business, which is self-funded, was largely on hold.

“Every manufacturer is at something of a standstill anyway,” he said. “This gave us something to do and a way to help even a little.”

The View from Los Angeles

On the West Coast, Mr. Charney began manufacturing his masks a few weeks ago, when he became aware of the growing shortage in the market. Because his company largely produces T-shirts and other apparel for the music and merchandising industry, many of his employees already wear masks to protect themselves from the dust involved in textile manufacturing. He began to look into designing his own products, and last week began production.

“These are not N95 masks, but they are the equivalent of surgical masks,” he said over the phone. Made from a sweatshirt-like fabric, they fit closely over the face and are held on by two straps with a metal adjuster on the nose. They are intended for reuse, which surgical masks are not, and are intended to be washed in hot water.

Mr. Charney is in talks with both federal and municipal agencies to supply large quantities of the masks. He said he had made deliveries to hospitals in Seattle, New Mexico, New York and Las Vegas. Hospitals in Los Angeles receive the masks free of charge; consumers can purchase them on the Los Angeles Apparel website for three for $30. (The C.D.C. recommends people wear masks if they are sick. People who are well do not need to wear masks, and are encouraged to save masks for caregivers.)

The approximately 450 people who work in Mr. Charney’s factory all wear the masks, as does any third party vendor who enters the space. They are all also subject to daily temperature checks — once upon entering and again later in the day — and efforts have been made to move the machinery farther apart to maintain social distancing, though Mr. Charney acknowledges that is “not always possible.” So far, no one has tested positive for the virus that causes Covid-19.

The decision to step up and begin manufacturing masks marks a return to public life for Mr. Charney, who has been lying low since his ouster from American Apparel in 2014.

The Next Frontier

Even beyond manufacturing, fashion companies are using their manufacturing networks to find masks.

Both Inditex and LVMH have used their distribution networks to gain access to Chinese manufacturers of face masks; LVMH announced on Saturday it had ordered 40 million face masks from a Chinese supplier, bound for France.

The first 10 million masks will begin arriving on Wednesday, and amount to 5 million euros, paid for by Bernard Arnault, chairman of LVMH. Inditex had shipped 10,000 face masks from China and were expected to ship another 300,000.

In New York, Kerby Jean-Raymond, the owner and designer behind the label Pyer Moss, also issued a call on Instagram for masks and other protective supplies.

He notes in his post that his sister is a nurse and that she and many of her colleagues “have not had enough N95 masks and some are without gloves.”

“My sister was exposed to Covid-19 and her elder patients’ safety have been compromised due to some professionals having to wear makeshift masks,” Mr. Jean-Raymond added.

Mr. Jean-Raymond said in the post he was converting the Pyer Moss office into a donation center for masks, gloves and gowns, and included an email address where medical officials in need could reach out. (Its address: wanttohelp@yourfriendsin.nyc.)

All of the brands involved in the masks programs are hoping their example starts a new trend.

“We are a tiny company,” Mr. Siriano said, continuing, “if a giant company with a lot of manpower were to take a similar initiative, it could change everything.”