Follow KDKA-TV: Facebook | Twitter

NEW YORK (AP) – U.S. health officials are again urging people to stop vaping until they figure out why some are coming down with serious breathing illnesses.

READ MORE: Pittsburgh Police Investigating Multiple Overnight Gas Station Armed Robberies

Officials on Friday said they had identified 450 possible illnesses, including at least three deaths, in 33 states. The count includes a newly reported death in Indiana.

READ MORE: Stimulus Check Update: Some May See Even More Money From Potential Economic Relief Package

Health officials say no single vaping device, liquid or ingredient has been tied to all the illnesses. Many of the sickened – but not all – were people who had been vaping THC, the chemical that gives marijuana its high.

A week ago, U.S. officials pegged the number at 215 possible cases in 25 states. Health officials have only been counting certain lung illnesses in which the person had vaped within three months. Most are teens.

MORE NEWS: Pittsburgh Home And Garden Show Postponed To October

(Copyright 2019 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.)