LOS ANGELES (AP) — California health officials are urging consumers to stop vaping of any kind until investigators determine why hundreds of people nationwide have been sickened after using the devices.

California health officials say 90 people who have a history of vaping were hospitalized for severe breathing problems and lung damage, and two people have died.

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With no known cause, officials say consumers should refrain from vaping marijuana or tobacco products until investigations are completed.

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Over 500 cases have been reported across the U.S., and the Centers for Disease Control and Prevention is investigating the mysterious outbreak but has not yet identified a common electronic cigarette or ingredient.

Acting State Public Health Officer Charity Dean says “we are seeing something that we have not seen before.”

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Symptoms include chest pain, nausea and vomiting.