A part of an apartment building collapsed in Atlanta due to an explosion on Sunday, rendering the three-story complex unstable and leaving at least one person injured, US media reports said.

The cause of the explosion is still unknown but according to Dunwoody Deputy Fire Chief Melvin Carter, Atlanta Gas had received a call from a resident of a strong odour shortly before the blast. One person with minor injuries was taken to a hospital for treatment, the Associated Press reported.

 90% of the building had been searched with two people reported missing. Carter informed that officials were in the process of shoring up the rest of the complex so that rescuers could continue searching for anyone who might be trapped inside.

The Dunwoody Police Department said that they received a report of an explosion at Arrive Apartments shortly before 1:30 pm. 

“At 1:24 pm, we received calls regarding an explosion at the Arrive Apartments. We are on scene with the Dekalb Co. and Sandy Springs Fire Dept. This is a very active scene and the cause of the explosion is under investigation. @DCFRpubaffairs will put out more when known,” police said in a statement on social media.

“The leasing office was collapsed on the left side, the double doors were blown out and I could hear a lady screaming her head off,” a witness told WSB-TV.

The witness said that she saw a couple of people limping and bleeding and being carried out of the rubble.

Police said they are working with fire departments to determine the cause of the blast. They asked complex residents not impacted by the explosion to remain in their apartments.

Dunwoody is a suburb just north of Atlanta.

(With AP inputs)