The investigation continued Monday into the fire that engulfed a four-story apartment complex in Buckhead on Sunday morning, forcing an emergency evacuation and sending one resident to the hospital.

Residents have not been allowed back inside the affected units, Channel 2 Action News reported.

The fire started at 7:18 a.m. Sunday at The Metropolitan at Buckhead complex at 3200 Lenox Road. About 35 units were destroyed, said Janet Ward, a spokeswoman for the Atlanta Fire Rescue Department.

Lenox Road was closed around Lenox Square Mall.

Firefighters were able to get everyone out of the building safely, with some requiring ladder rescues, Ward said. Quite a few pets were among those evacuated.

About 120 firefighters responded on the scene.

Two firefighters involved were taken to the hospital, one with heat exhaustion and the other with third-degree burns on a very small part of his neck, Ward said. Both will be fine, she said.

The Sandy Springs fire department sent firefighters to help, and firefighters from other local jurisdictions staffed Atlanta’s fire houses on Sunday.

Fire officials interviewed residents Sunday as they tried to determine what caused the fire.

Sixteen Red Cross disaster volunteers responded to the scene to help residents who lost their homes and belongings, said Sherry Nicholson, a Red Cross spokeswoman.

As of Sunday evening, Nicholson said, the volunteers were still meeting one-on-one with families and had already helped 31 families with a combination of food, clothing, shoes and lodging.