Gunman opened fire with a pistol in the waiting room of a medical centre, shooting five people, and then fled on foot.

The suspect, identified as Deion Patterson, 24, was taken into custody on Wednesday without incident after an undercover officer spotted him north of Atlanta hours after the midday shooting at the Northside Medical facility in the capital of the southern state of Georgia.

The motive for the shooting and whether the suspect knew or targeted any of his victims has yet to be determined.

“We know that he had an appointment at the facility, but why he did what he did – all of that is under investigation,” Atlanta’s deputy police chief of criminal investigations, Charles Hampton, said at a news briefing.

Atlanta Police Chief Darin Schierbaum told an earlier news conference that it was too early in the investigation to determine if the five women who were shot were patients or employees.

The woman who died was 39. The four wounded women ranged in age from 25 to 71, local media reported.

Three victims were in critical condition and underwent surgery. Schierbaum described them as “fighting for their lives”.

Hampton said the gunman opened fire with a pistol and was only inside the medical centre for about two minutes, then fled on foot and headed to a nearby petrol station, where he commandeered a pickup truck that had been left running unattended and drove away.

Police analysed a barrage of surveillance camera images and telephone tips from the public to ultimately narrow down the suspect’s location, Cobb County Police Chief Stuart VanHoozer said.

The gunman arrived at the medical centre with his mother, Schierbaum said, but she was not injured. Police said she and other family members were cooperating with investigators.

Atlanta Mayor Andre Dickens decried the shooting as the latest act of carnage in what has become “a national epidemic of gun violence” turning schools, workplaces, churches and doctors’ offices into potential killing zones.

He said active-shooter drills have become so common that a business in the area of Cobb County where Patterson was arrested happened to be conducting such an exercise as police closed in on the suspect nearby.

‘Those families, those families’

Patterson’s mother, Minyone Patterson, told The Associated Press news agency her son, a former Coast Guardsman, had “some mental instability going on” from medication he received from the Veterans Affairs (VA) health system that he began taking on Friday.

She said her son had wanted the drug Ativan to deal with anxiety and depression, but the VA would not give it to him because it said it would be “too addicting”.

“Those families, those families,” she said of the victims’ relatives as she started 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.”

Veterans Affairs Press Secretary Terrence Hayes said he could not discuss the case.

“We are horrified and saddened to hear of the active shooter situation in Atlanta today. Due to patient privacy, we cannot discuss the veteran’s personal information without written consent,” Hayes said in a statement.

US Senator Raphael Warnock of Georgia later took to the Senate floor to decry gun violence and urge his colleagues to advance gun reform.

“There have been so many mass shootings … that, tragically, we act as if this is routine,” he said. “We behave as if this is normal. It is not normal.”