Apple CEO Tim Cook tweeted Saturday that the company was donating “millions of masks for health professionals in the US and Europe,” to help combat the spread of the novel coronavirus. Cook’s tweet appears to confirm a statement earlier in the day by Vice President Mike Pence.

“The president and I literally heard directly from Apple that they’re donating 2 million industrial masks to this effort around the country and working with our administration to distribute those,” Pence said at a White House press briefing. A later briefing from Pence on March 24th would expand that number to 9 million donated masks, which Apple CEO Tim Cook would further clarify in a tweet to “10 million masks for the US and millions more for the hardest hit regions in Europe.”

Our teams at Apple have been working to help source supplies for healthcare providers fighting COVID-19. We’re donating millions of masks for health professionals in the US and Europe. To every one of the heroes on the front lines, we thank you. — Tim Cook (@tim_cook) March 21, 2020

According to Cook’s tweet, Apple’s operations team is using its supply chain knowledge to source, procure, and donate the masks, which helps explain how Apple was able to obtain so many masks in such a short time.

Globally, masks are in high demand, but supplies are running low. Amazon CEO Jeff Bezos said in a note to employees Saturday that “masks remain in short supply globally.” The company has “placed purchase orders for millions of face masks we want to give to our employees and contractors who cannot work from home, but very few of those orders have been filled,” Bezos wrote.

N95 respirators are disposable, close-fitting masks that can keep virus-laden droplets away from the wearer’s mouth and nose. The Centers for Disease Control and Prevention notes that the masks’ effectiveness is “highly dependent upon proper fit and use.”

Pence said Saturday that the Department of Health and Human Services “placed an order for hundreds of millions of N95 masks,” with the order coordinated through the Federal Emergency Management Agency. Where the masks were ordered from and when they would be available wasn’t clear from Pence’s remarks.

The shortage of personal protective equipment like face masks has become a serious problem for healthcare workers, with some resorting to using less-effective masks or even going without while treating patients, the New York Times reported. Last week, Pence called on construction companies to donate their protective masks to hospitals, and to refrain from ordering more. “Those industrial masks that they use on construction sites are perfectly acceptable for healthcare workers to be protected from a respiratory disease,” the vice president said at a briefing on Tuesday.

Fauci said more N95 masks will be available “sooner than weeks.”

But ProPublica reports there’s been confusion over how such donations would take place, and the White House hasn’t given clear instructions.

On Saturday, Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Disease, told reporters in the White House briefing room that it would be “sooner than weeks” for medical professionals to receive fresh supplies of masks. “We’re going to try to make it days to the best possible way that we can,” he said.

Some companies and individuals appear to have donated directly. On Twitter, director Peyton Reed thanked Tesla CEO Elon Musk for donating supplies— “a truckload of PPEs (masks, gowns, etc.)” — to a a UCLA Health facility. We reached out to Tesla to confirm that Musk was the one who sent the donation but have not heard back.

I want to publicly thank @elonmusk for sending a truckload of PPEs (masks, gowns, etc.) to UCLA Health today! They will be put to good use. My wife, her co-workers and her patients thank you profusely. pic.twitter.com/SiAdqMcPCT — Peyton Reed (@MrPeytonReed) March 22, 2020

And Facebook CEO Mark Zuckerberg said the company was donating an emergency reserve of 720,000 masks. “We’re also sourcing a lot more to donate,” he added.

Health workers urgently need more protective gear. To help, Facebook donated our emergency reserve of 720,000 masks that... Posted by Mark Zuckerberg on Sunday, March 22, 2020

Update March 22nd, 2:41PM ET: Added information from Peyton Reed and Mark Zuckerberg about donated supplies.

Update March 25th, 3:48PM ET: Added additional information from Tim Cook about donated supplies in Europe.