A Dunwoody apartment complex where an explosion took place Sunday had “appliance and fuel line issues within the building,” Atlanta Gas Light officials said Monday evening.

Natural gas crews called to investigate a report of a strange scent at the Arrive Perimeter apartments on Asbury Square were on the way to the scene when the building exploded about 1:30 p.m., an AGL spokeswoman said. Four people were injured in the blast, two severely.

As a result of the inspections, AGL “has been directed by the Dunwoody City Code Officer to suspend all natural gas service to the entire apartment complex until all units are inspected by a licensed plumber and deemed safe to operate,” spokeswoman Mekka Parish said Monday. Natural gas service will be cut off to more than 400 apartment units.

Dunwoody city officials said on social media that an onsite inspection revealed two additional gas leaks in a building at Arrive Perimeter that was not involved in Sunday’s explosion.

AGL is responsible for delivering natural gas to the property but does not maintain appliances and fuel lines within the buildings. Representatives from the Arrive Perimeter apartment complex have not responded to inquiries from The Atlanta Journal-Constitution or released any public statements.

The explosion left much of the complex’s 2000 building in rubble and left dozens of residents shaken. The cause of the incident remains under investigation.

On Monday, firefighters were still at the scene of the blast working to sift through the debris and wreckage that was left behind.

“Crews are working to clean up some of the damage to make it accessible for some of the residents in the back of the community,” DeKalb County fire department spokesman Capt. Jaeson Daniels said.

Four residents were injured, including one with a severe burn and one with a broken leg, Daniels said. They were both taken to Grady Memorial Hospital. No updates on their conditions were provided Monday. Two others were treated for minor injuries.

By the time fire crews arrived Sunday, the front side of the building had suffered “a tremendous amount of structural damage” from the blast, officials said.

“On arrival, they witnessed a partial collapse of the building ... they began to evacuate the remainder of the building in which they could access,” Daniels said.

The blast was so powerful that it blew apart a building and damaged surrounding buildings, Channel 2 Action News reported. Neighbors within a half-mile or so of the incident took to social media saying they heard the boom and even felt a rattle like an earthquake. The complex is about a mile northeast of Perimeter Mall.

Police evacuated residents while fire crews on the scene began searching the areas of the building that were structurally safe, being cautious to avoid a secondary collapse, authorities said.

DeKalb fire said no residents were trapped inside the building during the incident.

About 50 residents who lived in 25 different apartments were left displaced by the explosion, Daniels said.

“There are a few units that were significantly affected by the blast,” Daniels said. “They aren’t able to access those units. Those residents are not able to return just yet.”

The American Red Cross of Georgia is working to assist residents who were displaced.

Some residents told reporters that the smell of gas was an ongoing issue at the apartment complex and was reported to the property managers multiple times. In a statement, AGL told Channel 2 that the utility had not received any other calls to the property outside of the one they responded to Sunday.

Daniels said DeKalb fire is checking through its call logs to determine how many times they had been called to the complex, Channel 2 reported.