At least 380 people in 36 states have come down with a potentially deadly lung illness linked to vaping—and the U.S. Centers for Disease Control announced Monday that it’s stepping up its response. The agency activated its Emergency Operations Center so it can provide more support to staffers “working to protect our Nation from this serious health threat,” CDC Director Robert Redfield said in a statement. Six people have died from the vaping-related illness, but the exact cause is still unknown.