Health officials in the US have told people to stop vaping until they can determine if the smoking substitute is behind three more deaths and 450 cases of lung disease.
On Friday US time three deaths in Indiana, California and Oregan were reported as being linked to vaping. That brought the death toll to five that are thought to be vaping-related.
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The Centre for Disease Control and Prevention in the US said they were investigating 450 cases of lung disease that could be related to vaping across 33 states.
The CDC said the patients vaped either nicotine or the marijuana constituent THC.
"We are working around the clock to find out what is making people sick," Ileana Arias, the CDC's acting deputy director of non-infectious diseases, told ABC News.
"The focus of the investigation is narrowing, but we are still faced with complicated questions in this outbreak."
The Los Angeles County Department of Public Health confirmed it was investigating the city's first suspected vaping death.
"Stop vaping now, until further information in what is causing lung damage and death can be understood," Barbara Ferrer, director of the Los Angeles County Department of Public Health, told ABC News.
The Food and Drug Agency has collected 120 e-cigarette samples and is testing them to try and find a common substance that is causing lung disease.