ATLANTA (AP) — Police said a man opened fire inside the waiting room of an Atlanta medical facility, killing one woman and injuring four others Wednesday as authorities swarmed the city’s bustling midtown neighbourhood in search of the gunman.

Authorities said Deion Patterson, 24, stole a vehicle and fled after shooting five women on the 11th floor of a Northside medical building shortly after noon. The facility is in a commercial area filled with office towers and high-rise apartments and news of the shooting prompted workers and lunchgoers to shelter in place for hours.

“We believe (Patterson) carjacked a vehicle a short distance away and was able to flee the scene as the law enforcement agencies were descending on this area,” Atlanta Police Chief Darin Schierbaum said during a news conference.

Schierbaum said 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.

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.

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 12:30 pm, Cobb County police Sergeant 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 cooperative” with investigators.

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 for information leading to the arrest and indictment of the suspect.