An employee at a McDonald's in Knoxville faces a string of drug charges after he sold narcotics to undercover detectives at a Sunoco gas station yesterday, police said.

Police said Arnold J. Simpson, 30, of Arlington, sold drugs to undercover detectives several times and in several places, including at the McDonald's, 630 Brownsville Road in Knoxville, where he worked.

Mr. Simpson was on duty at McDonald's during one narcotics sale, they said.

During yesterday's arrest, at the gas station in the 1600 block of Arlington Avenue, officers said they recovered a .357 revolver, crack cocaine, the prescription painkiller Percocet, heroin, cash and a cell phone.

Mr. Simpson faces charges including crack possession and delivery, prescription drug possession and illegal possession of a firearm by a felon.

He was being held at the Allegheny County Jail yesterday.