The blast happened on the first floor of the Edgewater at Sandy Springs apartments in the 7600 block of Roswell Road.
A resident told Channel 2's Diana Davis she smelled gas then heard an the explosion.
"I was in my apartment and heard a huge explosion and everything literally went off the floor, up in the air, and came back down," said resident Sandy Jamerson.
When Jamerson outside, she said she found the walls of the apartment below her blown out, and a man yelling for help. He had been blow out into the parking lot, along with the wall of his unit.
The man said he opened the door to his apartment and it exploded, according to police. The victim is in his 30's, and was taken to Grady Memorial Hospital with non-life threatening injuries according to firefighters. The man had just moved into the apartment complex according to residents.
A natural gas leak is likely the cause of the explosion, police said. There was a small fire, but the force of the explosion blew the flames out, officers said.