UNION COUNTY, N.C. (QUEEN CITY NEWS) — An 18-year-old woman and her boyfriend were arrested in Union County this week after authorities seized cocaine, fentanyl and a stolen firearm that the two allegedly planned to use to rob an undercover detective, according to the Union County Sheriff’s Office.

Authorities said the investigation into Sophia Keller and 20-year-old John Jemisonmango, a convicted felon, began after investigators learned they were selling illegally street pressed pills containing fentanyl.

The sheriff’s office said deputies and other local first responders had been dispatched to at least one nearly fatal overdose within Union County as a direct result of Keller and Jemisonmango’s sales.

During the overdose, first responders reportedly administered multiple doses of Narcan to save the life of a juvenile. They are still recovering, authorities said.

To prevent future harm, the sheriff’s office said an undercover detective met with Jemisonmango and Keller at a shopping center in Weddington.

As the detective began to interact with the two suspects, other investigators converged on the vehicle and found Jemisonmango with a loaded, stolen firearm and a ski mask. Both suspects were taken into custody.

Authorities seized various drugs from their vehicle, including cocaine, a “trafficking quantity” of fentanyl, and the stolen gun, the sheriff’s office said.

Investigators said that they learned during an interview with the suspects that Keller and Jemisonmango planned to rob their potential buyer — the undercover detective — using the stolen firearm.

Keller is charged with felony drug trafficking and other charges. She was issued a $450,000 secured bond.

Jemisonmango is charged with felony drug trafficking and other charges. He was issued a $750,000 secured bond.