In recent e-cigarette news, the Food and Drug Administration (FDA) showed up at Juul’s headquarters in a surprise inspection last week.

The agency said that it seized “thousands of pages of documents” from the e-cigarette maker’s San Francisco headquarters, according to a Tuesday statement. The FDA added that it is examining how the company is conducting its marketing practices, which is an extension of a request the agency made in April, requesting that Juul shed more light on how it is making its products appealing to kids.

FDA Commissioner Scott Gottlieb said that teen use of e-cigarettes, or vaping, is an “epidemic.” The inspection took place on Friday and it “sought further documentation related to Juul’s sales and marketing practices, among other things,” the agency said in a statement.

Juul CEO Kevin Burns said that the company took the FDA through “every part” of its business, which includes the company’s marketing practices, as well as its age-verification tools that are available on its online shop. “It was a constructive and transparent dialogue,” Burns added in a statement.

Juul has control of about 73% of the e-cigarette market, garnering the FDA’s attention as teen use of e-cigarettes continues to increase every year. Among its various initiatives to curb teen use of nicotine products, the agency is considering banning flavored nicotine liquids as they are more likely to attract teenagers to vaping.