NASHVILLE (AP) — Tennessee health officials say they have received 49 cases of serious lung injury in people who use electronic cigarettes or other vaping devices.

The Department of Health said Monday that no single product has been linked to the cases and the specific ingredient causing the lung injuries remains unknown.

The state is recommending Tennesseans refrain from using vaping products as the investigation is ongoing.

The CDC reported earlier this month that the number of vaping-related illnesses in the U.S. has reached about 1,300, with at least 26 deaths. Most who got sick said they vaped products containing THC, the marijuana ingredient that causes a high, but others said they vaped only nicotine.

The CDC is advising Americans to refrain from using any vaping products.