ARTINGTON, Texas – A “Good Samaritan” with a gun killed a homicidal suspect (commonly referred to as an active shooter) who may have been gearing up for a deadly rampage at a Texas sports bar Wednesday night, police said.

When 48-year-old James Jones walked inside the Zona Caliente Sports Bar, started yelling and then reportedly shot and killed Cesar Perez — a 37-year-old restaurant manager who’d attempted to calm him down — Arlington police said witnesses were afraid they would be next, reported NBC News.

Police said that Jones not only had the gun used to shoot Perez, but he had a backup firearm and two knives as well. Unlike large numbers of licensed firearms carriers in Texas, Jones was not among them.

“He definitely had the capacity, if he wanted, to commit further violence and potentially kill other patrons in the business,” Arlington Police Lieutenant Chris Cook told NBC News, adding that it did not appear that the shooter knew his victim.

The Arlington Police Department referred to the citizen who intervened as an armed “Good Samaritan.” Fortunately for other patrons, the man happened to be eating at the restaurant with his wife. A concealed carry permit holder, he told her to get down on the ground and then shot Jones in the back.

“I don’t think the shooter even knew where the rounds were coming from because he started shooting at the front door,” Cook said, who described the scene as “chaotic.”

Police pieced together the chaos by reviewing video surveillance and interviewing witnesses. Yet it remains unclear how many shots either individual fired. Detectives are looking into Jones’ background to see whether he suffered from any mental illnesses and will need to await toxicology results to determine if he was under the influence of controlled substances or alcohol.

The man who took down Jones wished to maintain his anonymity, police said, noting that he felt overwhelmed but relieved that he prevented further violence.

“We’re thankful that the ‘Good Samaritan’ acted quickly and decisively to end the threat,” Cook said. “We never recommend people get involved. That’s a personal decision that a citizen has to make.”

Use of force and firearms expert Emanuel Kapelsohn told NBC News that, from his understanding, the man who took down the shooter reacted appropriately.

“I think it’s to be applauded,” he said. ”

Not everybody in the world ought to own a gun. Not everybody in the world ought to carry a gun. Not everyone in the world ought to engage an armed criminal where innocent people could be potentially injured.”

“But this Good Samaritan obviously had the ability to do what he did,” Kapelsohn added. “Who knows how many people would be dead if he had not acted?”