Two milligrams of fentanyl
The 2 milligrams of fentanyl shown here are enough to kill a person. Courtesy Drug Enforcement Administration

Investigators sought Wednesday to determine who supplied fentanyl to two South Bay teenagers who overdosed — one fatally — on the powerful narcotic last week.

The first of the two drug-related medical emergencies in Chula Vista took place Thursday afternoon, according to police. Paramedics saved the patient, a 16-year-old, by administering naloxone, a medication that blocks the effects of opioids.

“Officers later learned the (teen) was with friends and knowingly ingested a substance they believed to contain fentanyl,” Lt. Frank Giaime said. “The friends administered CPR prior to medics’ arrival.”

The next day, emergency crews responding to a second fentanyl overdose in the South Bay city were unable to revive the 17-year-old patient.

“During the death investigation that followed, officers learned the juvenile decedent was one of those present at the overdose incident from the day prior,” the lieutenant said.

The victims’ names and genders have not been released.

Anyone with information was asked to call San Diego County Crime Stoppers at 888-580-8477 or contact the agency online at sdcrimestoppers.org.

Tipsters may remain anonymous and could be eligible for a reward of up to $1,000.