SAN FRANCISCO (CBS SF) – Federal prosecutors have reportedly launched a criminal probe into San Francisco-based e-cigarette maker Juul Labs.

According to The Wall Street Journal, the U.S. attorney’s office of the Northern District of California is leading the investigation. The focus of the probe was not immediately known, the Journal reported.

Amid a vaping epidemic among teens, the company’s marketing practices have faced scrutiny from multiple agencies and several states, including the Federal Trade Commission and the Food and Drug Administration. Earlier this month, the Trump administration announced that it would ban sales of most flavored e-cigarettes.

San Francisco, Livermore and Richmond have approved banning the sales of e-cigarettes until the products are reviewed by the FDA. Meanwhile, Juul is fighting back by supporting ballot measures blocking the bans in San Francisco and Livermore.

Juul has not immediately responded to a request for comment.