BUTTE COUNTY, Calif. (KTXL) — An 18-year-old Oroville man was arrested Wednesday after investigators say he sold three juveniles counterfeit pills that contained fentanyl.

The Butte County Sheriff’s Office says Monday, a girl called to report her friends had overdosed on Xanax.

Deputies and emergency responders found the three juveniles at a home in Palermo and took them to a local hospital, according to the sheriff’s office.

The sheriff’s office says detectives with the Felony Investigations Unit, Butte Interagency Narcotics Task Force, Special Enforcement Unit and the Marine Unit launched an investigation to find the source of the pills, which they believed were counterfeit Xanax laced with fentanyl.

By Wednesday, investigators identified 18-year-old Knowa Massey as the person who allegedly sold the juveniles the pills.

A search warrant was served at Massey’s home on Grand Avenue in Oroville, where the sheriff’s office says detectives found a large number of counterfeit pills.

Investigators say they later learned Massey knew the pills were “extremely potent.”

The sheriff’s office says the 18-year-old was arrested and faces multiple charges, including possession of a narcotic substance for sale, child endangerment and committing felonies that caused great bodily injury. He was booked into the Butte County Jail.

His first court appearance is scheduled for 3 p.m. Friday.

Anyone with additional information about Massey has been asked to contact detectives at 530-538-7671. The sheriff’s office is also asking anyone with information about illegal narcotics sales to contact the Butte Interagency Narcotics Task Force at 530-538-2261.