The New York City Department of Health says that carfentanil, which is estimated to be 100 times stronger than fentanyl, has been found inside the five boroughs.

The health department's drug checking program revealed that carfentanil was found in eight different samples that were tested from March to June.

Data from the NYC Health Department's Bureau of Vital Statistics shows that carfentanil was involved in at least seven overdoses between January and June.