SAN FRANCISCO -- Nine San Francisco firefighters were taken a local hospital for evaluation Wednesday night after responding to a two-alarm fire that broke out in a high-rise building in city's Union Square neighborhood, a fire department spokesman said.

The fire was reported at about 6:55 p.m. in the 11-story Tiffany building at 360 Post St., fire Lt. Ken Smith said. Responding firefighters found heavy smoke on every floor of the building.

Fire officials evacuated the luxury jewelry retailer and went floor to floor searching the 11-story high rise for the source.

"We had every floor charred with heavy black smoke," said Lt. Smith. "It takes extensive amount of crews to get in here and search the building to find out where the smoke is coming from, as well as make sure that everyone is evacuated."

Smith said the fire, which was electrical in nature, was located in the basement of the building and extinguished by about 7:25 p.m.

The smoke and firefight attracted a crowd of spectators, among them long time Sir Francis Drake chief doorman Tom Sweeney, who called in the fire.

"There was so much smoke coming on Sutter street,” said Sweeney. “I didn't see flames, but tons of smoke."

Bob Mantia was working security at Nike's Women's Marathon event across the street when he saw the smoke and watched the firefighters swarm the Union Square landmark.

"I looked at the roof, there was smoke before I knew it there was smoke coming out but it was a lot heavier at the time," said Mantia. "Fire trucks racing around the blocks and they got here figured out where it was."

Approximately 100 firefighters responded to the incident and nine were taken to a local hospital for possible smoke inhalation, Smith said.

He said no merchandise inside the Tiffany store was damaged, but that the store would likely be closed Thursday because a large amount of smoke entered the business. The store comprises the first two floors of the building, Smith said.