FORT LAUDERDALE, Fla. -- The Fort Lauderdale fire marshal continues to investigate what caused a massive fire at an apartment building that left nearly 100 senior citizens homeless.

On Monday night, flames ripped through the Sunny Ranch Acres apartment building in the 100 block of Southwest 18th Avenue, sending 13 residents and two firefighters to the hospital.

The blaze started in a unit on the fourth floor and quickly spread, investigators said. When crews arrived, flames were shooting out of the windows, and dozens of elderly residents were struggling to escape the heat and smoke. Firefighters are credited with saving the lives of dozens of residents.

"During this incident, 60 rescues were made of occupants within the building out of the total of 100, six of which were brought down by firefighters with ladders," said Fort Lauderdale Fire Chief James Eddy.

Most of the victims suffered smoke inhalation, and were given oxygen before they were taken to Broward General Medical Center for treatment.

"I have no shoes on," said S.T. Cuff, who ran out of the building shortly after hearing the fire alarm go off. "My keys to my car are in there. My cell phone is in there. My wallet is in there."

The American Red Cross set up a shelter at the New Mt. Olive Baptist Church in Fort Lauderdale, where the lobby resembled a pharmacy Tuesday morning, as Red Cross workers doled out medicines firefighters recovered from apartments in the building.

Rosalyn Mehas, and her dog, Trixie, were waiting for word on when they could return home.

"I have no identification, no money, no nothing, just the clothes on my back," Mehas told Local 10's Roger Lohse.

The Red Cross is supplying basics for 47 residents staying in the shelter, but workers said the relief effort requires unique attention.

"We're dealing with a large elderly population. We've ordered food that's OK for diabetics, as well as people on low-sodium diets. We're trying to keep within those bounds so that everybody can eat the food that we serve," said Anika Bahr, a Red Cross volunteer.

It will be at least two days before the building will be reopened because investigators said the fire damaged the electrical system.

Several people have come forward to say a blind neighbor trying to put out a cigarette accidentally started the fire, but the investigation is ongoing, the fire marshal said.

"He was trying to get the fire extinguisher, but he's blind and can't see," said Ashley Tate, who was visiting her father's fourth-floor apartment when the blaze broke out.

All but one of the 13 residents taken to the hospital Monday night have been released. Two firefighters suffered leg injuries. They have also been discharged from the hospital.