A tenth death by fake Norco pills is now being investigated by Sacramento County officials.

The fentanyl pills disguised as Norco painkillers are responsible for at least eight reported deaths in Sacramento County and one in Yolo County. The death over the weekend brings Sacramento County fatalities to nine.

Those who have overdosed vary in age from 18 to 59, and are evenly split between men and women.

Fentanyl is considered 25 to 50 times more potent than heroin, and 50 to 100 times more potent than morphine. Officials aren't sure how they're being disguised as Norco painkillers.

As of Monday morning, 42 opioid-related overdoses have been reported, according to Sacramento County Department of Health and Human Services.

Additional information on the tenth death will be released later Monday, according to Sacramento Coroner Kimberly Gin.