One person was killed and three were injured in the southern US city of Atlanta on Wednesday when a gunman opened fire inside a building, police said, in the latest gun violence to hit the country.

Police were responding to "an active shooter situation inside a building" in central Atlanta, the department said on Twitter, in which four people were targeted.

"Three have been transported to the hospital for treatment and a fourth has been pronounced deceased on scene," it said.

Police also published a photo of the suspect, a well-built man wearing dark pants, a hood over his head and a white surgical mask, wielding a handgun.

"The suspect is believed to be armed and dangerous and should not be approached," police said.

Television footage showed police and other law enforcement officers deployed at the scene. Multiple ambulances were also present.

According to local television channel WSB, the shooting took place inside a facility of the Northside Hospital.

There have been more than 180 mass shootings -- defined as four or more people wounded or killed -- so far this year in the United States, according to the Gun Violence Archive.

With more firearms than inhabitants, the United States has the highest rate of gun-related deaths of any developed country: 49,000 in 2021, up from 45,000 the year before.