Gary Martin, 45, who died in a shootout with police after a rampage Friday that left five workers dead and at least six other people wounded, had his state weapons permit revoked years ago because of a felony assault conviction, police in Aurora, Illinois, said.

Still, they said, Martin’s gun — a .40-caliber Smith & Wesson handgun with a laser sight — was never taken away.

“Some disgruntled person walked in and had access to a firearm that he shouldn’t have had access to,” said Kristen Ziman, chief of police in Aurora, where the shooting took place as Martin was being fired.

Ziman said that the police were trying to determine why Martin still had a gun, despite having his permit revoked five years ago.

According to Illinois gun law, a person must be granted a Firearm Owners Identification card, or FOID, to possess a firearm. At least 2 million people in the state have the cards.

But under the law, the process of removing firearms from people whose cards have been revoked is weak, making it easy for some to keep their weapons with little threat of enforcement or penalty.

That appears to have been the case with Martin, who police said received a card in January 2014. That March, he applied for a concealed-carry permit, and a background check revealed that he had a felony conviction for aggravated assault in Mississippi from 1995. With that, the Illinois State Police revoked Martin’s card and mailed him a letter ordering him to relinquish his firearm and card within 48 hours.

The statute allows law enforcement agencies to petition the courts to seize weapons if they aren’t turned in, but in many instances, the remaining weapons go unchecked. Experts said that the state rules — without a clear, mandatory enforcement requirement — leave a gaping loophole for those who choose not to give up their guns. In 2016, only about 4,000 of the 11,000 people whose cards were revoked submitted the mandatory reports explaining what they did with their guns, The Chicago Tribune reported in 2017.

Sgt. Bill Rowley, a spokesman for the Aurora Police Department, said police had no record of being notified by the state police that Martin had not volunteered his firearm as required in 2014. It was unclear whether Martin, who lived in Aurora at the time of his death, also lived there in 2014.

The police on Saturday gave a fuller account of the deadly events inside the Henry Pratt Co. warehouse on Friday afternoon, and identified the five workers — all co-workers of Martin — who were killed.

The victims included some of the company’s most experienced workers but also its newest: Josh Pinkard, who was the plant manager of the warehouse, was killed in the shooting, as was Trevor Wehner, who was a student at Northern Illinois University and an intern in the company’s human resources department. Wehner was expected to graduate from college in May. Friday was the first day of his internship, according to officials from Northern Illinois University.

“He knew he wanted to work in the HR business and was hoping this internship would lead into a full-time job in the future,” said Winter Lane, Wehner’s girlfriend of more than three years, who grew up with him in the same small town of Serena, in north central Illinois.

Everyone there knew Wehner. He was kind, the most selfless person she had ever met, she said, someone with a big smile and a personality to match. “He always saw the good in everyone,” she said.

Also killed, police said, were Vicente Juarez, stock room attendant and forklift operator; Clayton Parks, human resources manager; and Russell Beyer, mold operator. Officials at Northern Illinois said that Parks had also graduated from the university, in 2014, and that it was offering counseling help to those in need. (The school, in DeKalb, Illinois, was the site of another mass shooting 11 years ago.)

Abby Parks, wife of Clayton Parks, said he was devoted to their son, Axel, who is 8 months old. “The family we created together was Clay’s greatest joy,” she said. “He took his responsibilities as a husband and father very seriously and held those titles above all else.” The couple had been married since 2016.

Police first received several 911 calls at 1:24 p.m. Friday, as frantic callers said there was a shooter at the warehouse. Martin had been summoned to what police described as a “termination meeting” at the warehouse where he had worked for at least 15 years. At least two victims were shot at the scene of that meeting.

Four minutes later, police arrived and were confronted by the gunman. Two of the first four officers to arrive were shot and transported to hospitals with injuries that were not life-threatening.

According to police, Martin then retreated into the 29,000-square-foot building, hiding from officers in a machine shop near the back of the facility. It took about 90 minutes for officers to find, shoot and kill him.

Scott Hall, CEO of Mueller Water Products, of which the Henry Pratt Co. is a subsidiary, said that Friday was “the worst day our company has ever had.”

Martin was being fired on Friday for a “culmination of various workplace rules violations,” he said, declining to describe the violations. The firing came at the end of a “progressive discipline process,” he said.

The company conducted a background check upon Martin’s hiring 15 years ago that did not surface his felony conviction in Mississippi.

Before Friday, there was no indication that Martin was violent. “If we have reason to believe that somebody is going to be violent, we take precautions,” he said. “I can only assume that we did not.”

Family members of Martin arrived at the Aurora police station Friday afternoon, weeping and hugging one another after officers told them that he was dead.

“He was the shooter,” said Tameka Martin, who said she was Martin’s sister. “He shot officers. If they did shoot him and kill him, they were, I guess, defending themselves.”

Martin said that her brother had told his family that he had lost his job at Henry Pratt. At dinner a few nights ago at their mother’s home, Martin would barely speak about it. He was “very depressed,” she said.