D.C. Fire Chief Dennis L. Rubin said Friday that "it's very possible" someone put furniture in the hallway of a Mount Pleasant apartment building to keep people from escaping a fire there this week.

Investigators said they think that Wednesday morning's fire started in the fifth-floor hallway, where a mattress and other furniture were found. It killed one man who tried to jump to safety and injured 10 others, including a 2-year-old girl with burns on 30 percent of her body. She is in guarded condition at Shriners Hospital for Children in Boston, a pediatric burn center.

Rubin said fire investigators are still looking into all possible accidental causes before ruling the blaze an arson. Most likely, though, "this will be some sort of set fire," he said. The mattress, he said, might have helped fuel the fire.

Speaking at the firehouse of Engine Company 24's Rescue Squad 2, which sent a number of emergency responders to the blaze, Rubin asked for patience as investigators finish conducting interviews and collecting evidence. He said that officials had several "what we would call suspects or persons of interest" but that no one is in custody.

Among other victims taken to hospitals after the fire, three were released, and three remain in critical condition, said Pete Piringer, spokesman for D.C. Fire and Emergency Medical Services. He was not certain of the conditions of the others.

Rubin praised the efforts of the 125 firefighters and emergency responders from across the District, specifically those of Rescue Squad 2, who he said faced difficult conditions in their attempt to save dozens of people.

Firefighters were called to the 63-unit Sarbin Towers apartments, in the 3100 block of 16th Street NW, at 3:45 a.m. They escorted dozens of people out of the eight-story building, carrying some through smoke-filled hallways or down ladders.

Heat, smoke, language barriers and residents' panic made rescue efforts challenging, according to the firefighters. Brian Phillips described having to forcibly enter an apartment on the fifth floor, where he found a man who had removed a cable from his television, tied it to the refrigerator door and was "sitting on his window ledge, grasping it with both hands."

"That was his last-ditch effort," Phillips said. "to go out the window."

Capt. Timothy Jeffery said he knew things were bad when he saw "bloody footprints coming across the lobby area" as he entered the building. People were gathered at the windows of nearly every apartment he entered "just trying to get fresh air," he said.

"At some point, when [the window is] their only egress, who knows what's going to happen," he said.

Three people tried to climb down a tree from their fifth-floor apartments, said firefighters who were able to block one of them. Another person made it to safety, but one fell and died.