According to the Associated Press, the number of vaping related illnesses in the U.S. could soon climb much higher.

The Centers for Disease Control and Prevention believes that hundreds of more lung illnesses have been reported to health authorities since last Thursday, when the CDC put the tally at 530 confirmed and probable cases.

The CDC is investigating the little understood outbreak but has not yet identified a common electronic cigarette or ingredient.

Massachusetts recently ordered a four month halt to sales of all vaping products and devices. The temporary ban is the first of its kind in the nation. Michigan and New York have targeted their bans to vaping flavors.

The CDC is recommending people who vape consider not using e-cigarettes at all while authorities investigate.