"Nine brave, heroic, courageous firefighters of the city of Charleston have perished fighting fire in a most courageous and fearless manner, carrying out their duties," Charleston Mayor Joseph P. Riley said at a morning news conference. "To all of their loved ones, our heart goes out to them."

Two employees in the building were rescued from the blaze, which broke out at about 7 p.m. Monday in the Sofa Super Store and warehouse, Riley said.

Overnight, firefighters, police officers and other rescue workers saluted as the bodies were carried from the warehouse.

"To lose nine is just a tragedy of immense proportions," Riley said. "To lose nine is just unbelievable."

Riley said the county coroner planned to disclose the names of the dead. The cause of the fire was under investigation, but Riley said arson was not suspected.

He said the blaze apparently started in a storage area. He was unsure whether there were sprinklers in the building.

Witnesses said the store's roof collapsed, throwing debris over about two-dozen rescue workers. Onlookers were hit with flying ash.

"It was like a 30-foot tornado of flames," said Mark Hilton, who was struck in his eye.

Daniel Shahid, a salesman at a nearby car dealership, said firefighters came in asking for towels.

"The next thing you know, we were carrying hoses, directing traffic, everybody from the dealership," he said.

Shahid said he saw firefighters rescue four people from the building.

"They were struggling. They were covered in black soot. They looked scared out of their minds," Shahid said.

He later told CNN the roof collapsed too quickly for anyone to escape.

"It came from nowhere," he said. "It was a standing structure and five seconds later it was on the ground."

Riley called the firefighters heroes.