Five people were rescued from an apartment complex fire in Dallas early Sunday morning, fire officials told CBS News Texas.

According to Dallas Fire-Rescue, at about 1:50 a.m., crews were called to The Garrison apartments located in the 9900 block of Whitehurst Drive. When they arrived, firefighters saw heavy flames and smoke coming from the roof of a three-story building with reports of residents trapped inside. 

DFR said crews began a search and rescue, and five people were rescued. Two of those victims were transported to the hospital with minor injuries. 

A second alarm was called at about 2 a.m., bringing more crews to the scene to fight the fire from a defensive stance. It took more than two hours to extinguish the blaze, DFR said in a news release. 

DFR believes the fire was accidental and said it began on a first-floor apartment balcony, where combustibles were left too close to a heat source. 

"From there, the fire spread the height of the building to the roof before spreading across the entire attic space," DFR said in a statement.  

DFR said in total, 36 apartments were in the building, and all of them are uninhabitable due to varying degrees of fire, smoke and water damage.  The American Red Cross is assisting the residents who have been displaced, which is about 20 people.