Federal authorities have begun a criminal investigation into e-cigarette giant Juul Labs, according to the Wall Street Journal.

It’s not entirely clear what the investigation into the vaping company is all about, but according to the Journal, it’s being handled by the U.S. Attorney’s Office for the Northern District of California. The investigation is the latest in a string of bad news for the vaping industry: Between bans on products, a myriad of investigations, and an increasing number of illnesses and fatalities linked to e-cigarettes, the government has been stepping up enforcement against vaping as a whole.

The reported investigation could have huge repercussions for vaping: Juul is the single-biggest e-cigarette company in the United States, dominating about three-quarters of the market last year.

The company has been under fire from all sides as of late — it’s facing probes from state authorities, along with Federal Trade Commission (FTC) and Food and Drug Administration (FDA) investigations. Both state attorneys generals and the FTC are looking into whether Juul  targets minors with its marketing and flavored e-cigarettes.

Along with a specific investigation into Juul, the FDA has launched a separate criminal probe into the recent spate of vaping-related illnesses and deaths. Eight people have died from vaping-related lung illness so far. The most recent confirmed death was announced by health officials in Missouri on Thursday. At the same time, at least 530 people suffered lung damage from vaping as of September 11, according to the Centers for Disease Control and Prevention.

The latest investigation is part of a recent focus on vaping by federal officials. One of the biggest clouds on the horizon for vaping could be President Donald Trump, who said earlier this month that his administration would ban flavored e-cigarettes in order to curb teen vaping. Several states, including Michigan and New York, have moved to ban flavored vaping products as well.