The Centers for Disease Control and Prevention said that probable cases of the mysterious vaping-related lung illness have jumped from 380 to 530, and that number is still expected to rise. CDC Principal Deputy Director Dr. Anne Schuchat said that the death toll remains at seven. Food and Drug Administration officials also announced that the agency’s Office of Criminal Investigations unit has opened a probe focusing on the “supply chain.”

“This is an ongoing outbreak, not something we can consider completed,” Schuchat told reporters Thursday morning. Health officials are still unable to determine the precise cause of the illness, and have yet to single out one ingredient or brand responsible. “I wish we had more answers,” Schuchat said. CDC officials said Thursday that nearly three-quarters of the cases involve men, and two-thirds of those affected are between 18 and 34. “More than half of cases are under 25 years of age,” Schuchat explained.