Authorities in Houston are warning first responders to be ready to treat patients who have ingested what's described as "America's deadliest drug."
NBC affiliate KPRC reported officers recently seized 80 grams of a powerful opioid called carfentanil. Forensic specialists said it was enough for 4,000 lethal doses.
The drug is typically used to sedate elephants, but dealers have been using it as a cheap way to cut their supplies of opioids like heroin or pain medications.
Carfentanil is 100 times more powerful than fentanyl and 10,000 times more potent than morphine, the report said.
One grain of powder, which looks similar to table salt, can be fatal, according to Houston police.
"Leave these opioids alone, stay away from them and stay away from people who are using them," Houston Mayor Sylvester Turner said in a Tuesday news conference.