The Food and Drug Administration is tightening its leash on e-cigarette giant Juul Labs. On Friday, the FDA conducted a surprise inspection of the company’s headquarters, and took thousands of pages of documents in the process, CNBC reports.

The inspection was part of the FDA’s efforts to curb youth vaping, the agency says in an email to The Verge. “The new and highly disturbing data we have on youth use demonstrates plainly that e-cigarettes are creating an epidemic of regular nicotine use among teens,” the FDA says.

Back in April, the agency asked Juul to turn over information that might explain why the devices are so popular with young people. And on Friday, inspectors went to find documentation about Juul’s sales and marketing tactics for themselves. The inspection “resulted in the collection of over a thousand pages of documents,” the FDA says.

“E-cigarettes are creating an epidemic of regular nicotine use among teens.”

The FDA also inspected Juul’s contract manufacturing facilities earlier this year to check if they met FDA requirements, the FDA says. And just over two weeks ago, the agency gave an ultimatum to Juul and four other companies that manufacture the popular e-cig brands Vuse, MarkTen XL, blu, and Logic: the companies have until mid-November to prove that they can keep kids from using their vapes, or else face having their flavored products taken off the market.

In a statement emailed to The Verge, Juul Labs CEO Kevin Burns says the company still plans to present the company’s “plan to address youth access in the 60-day time frame as outlined by FDA.” Burns characterizes the company’s interactions with the FDA last week as “a constructive and transparent dialogue,” and says Juul Labs has turned over 50,000 pages of documents to the FDA since April. “The meetings last week with FDA gave us the opportunity to provide information about our business from our marketing practices to our industry-leading online age-verification protocols to our youth prevention efforts,” he says.

News of the raid comes on the same day as a report that confirms Juul really is taking over. Researchers with the Centers for Disease Control and Prevention tracked e-cigarette sales in brick-and-mortar stores, and found that from 2013 to late 2017, British American Tobacco — which makes the Vype line of vapes — dominated the market. But from 2016 to 2017, Juul’s sales spiked by 641 percent to 16.2 million e-cigarettes in 2017. By December 2017, Juuls made up the biggest share of the market, according to the paper published today in the journal JAMA.

That particular study didn’t address who was buying the vapes, or how old they were. But the researchers note that “Juul’s high nicotine concentration, discreet shape, and flavors could be particularly appealing to, and problematic, for youths.” And the FDA says it’s time to figure out what’s driving the epidemic of youth vaping, and stop it: “It is vital that we take action to understand and address the particular appeal of, and ease of access to, these products among kids.”