The U.S. Food and Drug Administrations criminal investigations unit is looking into the rise of vaping -related lung illnesses amid a nationwide outbreak thats linked to 530 illnesses and seven deaths , health officials said Thursday.

The announcement follows an increase in the number of confirmed and probable cases of illnesses related to vaping reported by the Centers for Disease Control and Prevention. The number of cases has increased by 150 since last week. The death toll is also expected to rise, health officials said.

The FDAs Office of Criminal Investigations, which began probing the illnesses shortly after people started falling ill, will focus on identifying what is making people sick as well as focus on the supply chain, Mitch Zeller, director of the FDAs Center for Tobacco Products, told reporters in a call.