LOS ANGELES COUNTY (KABC) -- Public health officials are investigating the first known death in Los Angeles County related to the use of e-cigarettes, also known as vaping.A total of 12 cases of vaping-associated pulmonary injury have been reported in the county since Aug. 14, according to the Los Angeles County Department of Public Health. Those reports are all from people with a history of vaping who experienced severe and sudden lung disease and required hospitalization.The person who died was described as an older adult who had chronic underlying health conditions, but at a Friday afternoon press conference, officials said it was clearly believed that vaping was the potential cause of death. This is the fourth death in the country linked to vaping.In the 12 cases, two-thirds are teens and young adults, while the remaining people are middle-aged or older adults over the age of 55, according to Muntu Davis, MD, MPH, Los Angeles County Health Officer."It is impacting everyone. For our younger adults, they are typically more healthy and don't have underlying health conditions so this is really crossing the gamut of age group and health," Muntu said.In all of the cases, the people used either a cannabis-based product, except for one who also used nicotine-based vaping products. Muntu added that it's unclear whether the cases were a result of the vaping liquid itself or a separate substance possibly being added to the vaping liquids."We can't link this to one product and we can't link this to one device," said Dr. Barbara Ferrer, the director of the L.A. County Department of Public Health.The department is urging the public to stop vaping "until further information about what is causing lung damage and death can be understood" amid an increase in cases across the nation."We're on record as the health department of noting that in fact, e-cigarettes has really set us back years in our struggle to eliminate addiction to nicotine and tobacco products among our young people," Ferrer said.U.S. health officials said they had identified 450 possible cases of serious breathing illnesses associated with e-cigarettes in 33 states. The count includes newly reported deaths in Indiana and Los Angeles County.