Maine police are warning of a new synthetic opioid that's far more powerful than drugs that are currently being used by addicts.

Sanford police said W-18 appears as a white powder that looks like heroin or fentanyl, but it's 10,000 times more potent than morphine and 100 times stronger than fentanyl.

The drug is similar to a drug used to tranquilize large animals, such as bears and elephants.Sanford Police Chief Thomas Connolly says the drug is already present in New England. Officials say two out of eight W-18 heroin overdoses in Massachusetts last weekend were fatal. (AP)