Grand Rapids police are warning people about a deadly drug combination.

It includes fentanyl mixed with cocaine and heroin, according to a news release. Fentanyl is a synthetic opioid that is 50 to 100 times as potent as morphine. Since July, the Grand Rapids police have had six cases involving the drug.

The department says that because of its rapid rate of absorption into the human body, the amount equivalent to the size of a few grains of table salt can be deadly.

The Grand Rapids Police Department offered these resources to deal with addiction.