Police say they have apprehended a man who allegedly opened fire inside the waiting room of an Atlanta medical facility, killing one woman and injuring four others on Wednesday afternoon.

Authorities had swarmed the city’s bustling midtown neighbourhood in search of the suspect, who fled after the shooting. Police said in a statement that the gunman, who they identified as 24-year-old Deion Patterson, was captured on Wednesday evening. Authorities did not immediately release additional information about where Patterson was found.

A 39-year-old woman was pronounced dead at the scene of the shooting. The four injured victims were also women, aged 25, 39, 56 and 71.

Police had said that Patterson’s family co-operated with investigators.

Those four “are fighting for their lives at Grady Hospital,” Atlanta Mayor Andre Dickens told reporters.

Police asked anyone with information about Patterson’s whereabouts to call 911 and not approach him.

Atlanta police said a suspected shooter in downtown Atlanta is believed to be Deion Patterson. Photo / AP

Patterson’s mother, Minyone Patterson, told The Associated Press by phone that her son, a former Coast Guardsman, had “some mental instability going on” from medication he received from the Veterans Affairs health system that he began taking on Friday. She said she didn’t know where her son was.

She said her son had wanted Ativan to deal with anxiety and depression but that the VA wouldn’t give it to him because they said it would be “too addicting”. She’s a nurse and said she told them he would only have taken the proper dosage “because he listened to me in every way.

 “Those families, those families,” she said, starting to sob. “They’re hurting because they wouldn’t give my son his damn Ativan. Those families lost their loved ones because he had a mental break because they wouldn’t listen to me.”

She ended the call without saying what medication her son had been taking.

After getting information that the shooter may have entered Cobb County, investigators checked surveillance and traffic cameras and found that the vehicle that appeared to be the one he was driving had entered Cobb County around 12.30pm, Cobb County police Sgt Wayne Delk said. That discovery set off a massive search in the county just northwest of Atlanta, but there had not been a confirmed sighting on camera or by any eyewitness since then, Delk said.

“We do believe that he might still be in the area,” he said, stressing that people should not approach if they see Patterson but should call 911.

Delk said Atlanta police recovered the vehicle in a parking garage near the Battery, a mixed-use development which is next to the stadium where the Atlanta Braves play.

“This is a very active search,” Schierbaum said. “We’re following up on credible leads that are currently active in Cobb County, as well as some here in the city.”

Schierbaum added that Patterson’s family is “being co-operative” with investigators.

Atlanta police said a suspected shooter in downtown Atlanta is believed to be Deion Patterson. Photo / AP

In a statement, the US Coast Guard said Patterson had joined the service in 2018 and was discharged from active duty in January. He was an electrician’s mate second class at the time.

Crime Stoppers was offering a reward of up to $10,000 ($16,000) for information leading to the arrest and indictment of the suspect.

Around the time of the shooting, Cassidy Hale, a medical device representative, said she was driving to the facility to check on a machine in the building’s 12th-floor outpatient surgery centre.

Hale saw fire trucks but didn’t realize anything was wrong until after she parked and found the elevator wasn’t working. Hale said she called the operating room manager, who told her there was an active shooter and she should go back to her car.

Hale said police kept her from leaving the parking garage and later checked each car and escorted her out to be interviewed.

She then gathered with other employees and patients in a building across the street, where she said “everyone was really in shock” and “trying to process what was going on.”

A medical patient is helped away from the scene of an active shooter in Atlanta. Photo / AP

The shooting comes as cities around the US have been wracked by gun violence and mass shootings in 2023.

Shortly after the shooting, Raphael Warnock of Georgia took to the Senate floor to decry gun violence and to urge his colleagues to advance gun reform.

“There have been so many mass shootings ... that, tragically, we act as if this is routine,” the Democrat said during a 12-minute speech. “We behave as if this is normal. It is not normal.”

The Atlanta pastor added: “I shudder to say it, but the truth is, in a real sense, it’s only a matter of time that this kind of tragedy comes knocking on your door.”

Georgia’s other US Sen. Jon Ossoff, also a Democrat, echoed his colleague in a statement issued Wednesday evening: “The level of gun violence in America today is unconscionable and unacceptable, and policymakers at all levels have a responsibility to ensure public safety and implement long-overdue reforms.”