After more than 100 overdose deaths over two months, the federal Substance Abuse and Mental Health Services Administration (SAMHSA) has alerted the addiction treatment community about a deadly combination of heroin and fentanyl, USA Today reported June 9.

"There's starting to be some increased awareness at the higher levels of government," said Robert Lubran, director of SAMHSA's division of pharmacologic therapies.

The U.S. Drug Enforcement Administration (DEA) issued a warning last month about the heroin-fentanyl mix, a potent blend that has been traced to scores of overdoses and deaths in cities from Chicago to Philadelphia to St. Louis.

A recent raid on a drug lab in Mexico was touted as dealing a blow to the source of the fentanyl, and some city officials say that the crisis appears to have peaked.