A gun-carrying citizen prevented an armed robbery at a north Phoenix pharmacy Tuesday by shooting and killing the suspect who was holding a gun to pharmacy employees.

AZCentral reported that Phoenix Police spokesman Sgt. Jonathan Howard said the incident occurred at 6:20 p.m. at a Walgreens on West Union Hills Drive. Howard said a man had jumped the pharmacy counter, pointed a gun at employees, and demanded Oxycodone, a strong painkiller.

According to Howard, an armed customer who was in the building drew his firearm and shot the suspect, wounding him.

Howard said officers reportedly arrived shortly after and found the scene "full of chaos." Police quickly escorted shoppers out of the building.

Janice Gordon-Caddy, a bystander who arrived at 6:45 p.m., said she “saw the workers from the pharmacy running out with their hands raised in the air. They were crying and screaming.’’

“Next thing I know, the SWAT team and all the police officers and everybody are going in with their guns; it was just a madhouse,’’ Gordon-Caddy said. “That probably would have been much worse if there hadn’t been a customer in there armed.”

Police said they found the suspect alive and armed, but gravely wounded. A K-9 unit was used to pry the firearm from the suspect's hand. Police attempted to administer CPR, but the suspect died on the scene.

The armed citizen, as well as witnesses, were held for questioning.

The names of the suspect and the armed civilian have not been released by police.

According to Arizona's Department of Public Safety, 318,988 concealed carry permits are currently active in the state, with 109,797 of these active in Maricopa County alone.