Federal and industry officials are stepping up efforts to avert potentially serious drug shortages in the aftermath of Hurricane Maria’s assault on Puerto Rico, a major center for pharmaceutical manufacturing.

Scott Gottlieb, commissioner of the Food and Drug Administration, headed to the island Friday morning with staff from the Department of Homeland Security. Gottlieb was scheduled to meet with the FDA’s 100 employees in San Juan and learn more about damage to the island’s dozens of drugmaking plants.

The agency is closely tracking 40 high-priority drugs that are deemed essential and could run short nationally if disruptions in manufacturing and distribution continue. About a dozen of the medications aren’t produced anywhere else. The agency declined to name the specific drugs.

“It’s a serious situation,” Gottlieb said in an interview before leaving. Should facilities not resume normal operations soon, “there’s a potential for shortages in critical products.”

As the vast scope of damage in Puerto Rico became clear this month, federal and industry officials have been working on shifting some manufacturing to the mainland, getting clearance for more private planes to land with supplies and take out finished products and assessing fuel needs for plants that soon may need them for generators.

Puerto Rico is home to about 50 pharmaceutical plants operated by Baxter, Pfizer Inc., Merck, Eli Lilly, Johnson & Johnson, Bristol-Myers Squibb, Amgen and other companies. The facilities produce treatments for cancer, high cholesterol and HIV, as well as immunosuppressants for patients with organ transplants. About 30 medical-device facilities also are located on the island.

Since Hurricane Maria’s battering, most of the pharmaceutical facilities have been operating at sharply reduced capacity. Getting an exact picture is difficult, according to federal and industry officials, because there is no cellphone service, and communications are poor.

Many of the pharmaceutical plants weren’t seriously damaged and retain the ability to refrigerate their products. But with the power grid knocked out, the factories are relying on diesel-fueled generators and running at significantly reduced capacity, according to officials. And many employees, struggling with the disaster’s effects on their families and homes, still aren’t able to get to work. Ground travel remains difficult because roads were washed away.

“It’s a dynamic situation,” said Nicolette Louissaint, executive director of Healthcare Ready, a group founded by drug manufacturers, distributors and others to protect patient access to medicines during emergencies. “There has been a 97 percent power loss and massive logistical challenges confronting the entire health-care response.”

Pharmaceutical manufacturing has been a cornerstone of the island economy for years, with much of the growth fueled by a tax break enacted in 1976. While some plants closed after the tax break expired in 2006, drug manufacturing still represents a whopping 72 percent of Puerto Rico’s 2016 exports, or $14.5 billion, according to the U.S. Bureau of Labor Statistics. The sector employs 90,000 people.

Gottlieb plans to deliver additional satellite phones to the FDA staff there to boost communications. He also said he wants to work with federal and local officials to determine which plants most urgently need diesel fuel.

“We don’t want to prioritize a manufacturing facility over a critical need for the local population unless it’s absolutely urgent for public health,” Gottlieb said.

Baxter International Inc., which makes several products in Puerto Rico, sent a letter to customers last week saying that it had lost “multiple production days” for sodium chloride and dextrose as a result of Hurricane Irma and then Maria. Pharmacies primarily use the products to compound or mix medications, a spokesman said.

The company is using a helicopter to ferry supplies and personnel to and from facilities, he added, while “proactively communicating with our customers about the actions we are taking to minimize potential disruptions, including closely managing product inventory.”

AbbVie, which manufacturers the blockbuster rheumatoid arthritis drug Humira in Puerto Rico, said in a statement that its facilities were “intact and operational” and running on generators. The staff was working “diligently” to restore normal operations and U.S. patients were unlikely to be affected, it added.

Eli Lilly spokesman Greg Kueterman said the company’s manufacturing facilities on the island, which make insulin and some non-diabetes oral medications, “sustained only minor damage, so they are ready to operate and we don’t anticipate any supply issues to the global markets.”

But the plant is not operating at the moment. “We’ve got power, but the infrastructure is really broken down, so not everyone is able to get there — and obviously people are dealing with their own home situation, families and things like that,” Kueterman said.

Earlier this week, Amgen said its preliminary assessment was “that the critical manufacturing areas in our facility in Juncos, Puerto Rico, have not been significantly impacted by this storm.”